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1963

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RESEARCH HIGHLIGHTS

O F TH E

NATIONAL BUREAU OF STANDARDS

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ANNUAL REPORT

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The groups to be served by the specialized services of the National
Bureau of Standards were well defined by the Congress at the time
the Bureau was founded. The Committee on Coinage, Weights and
Measures in recommending to the House of Representatives in May
of 1900 that a National Bureau of Standards be established, said :

"It is therefore the unanimous opinion of your committee that no more
essential aid could be given to manufacturing, commerce, the makers of
scientific apparatus, the scientific work of the Government, of schools,
colleges and universities, than by the establishment of the institution pro-
posed in this bill."

This statement, which provides an enduring focus for the activities of
the Bureau, will be engraved in stone in the lobby of the Administra-
tion Building at the new laboratory site near Gaithersburg, Maryland.

A. V. Astin, Director,
National Bureau of Standards.

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UNITED STATES DEPARTMENT OF COMMERCE

Luther H. Hodges, Secretary

J. Herbert Hollomon, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS
A. V. Astin, Director

1963
Research Highlights

of the

National Bureau of Standards

Annual Report, Fiscal Year 1963

December 1963

Miscellaneous Publication 255

For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, D.C., 20402 - Price $1.00

Library of Congress Catalog Card Number: 6-23979

Contents

Page

1. General review 1

Basic measurement standards 2

Standard reference data 7

National Standard Reference Data System 8

Engineering measurement standards 9

Standard reference materials . 11

Special central missions 14

Radio propagation 14

Data-processing systems 15

Building research 15

Consulting services 15

Background research 18

Internal support activities 19

International activities . . . . 19

Administrative activities 21

Publications and technical information 24

2. Highlights of the research program 26

2.1. Physics, electronics, and measurement standards 26

2.1.1. Metrology 26

A new standard of spectral irradiance 27

Basis for color measurement amended 27

Calibration of flashtubes 28

Fluorescent lamp measurements intercompared 28

Equipment developed for calibrating thermal detectors 28

Equipment developed for densitometric calibrations 29

Refractive index of calcium fluoride 30

Generalized lens-bending procedure developed 30

Technique for deriving principal curvatures of wave fronts ... 30

Image evaluation 31

Measurement of wave fronts 31

Stored microfilms inspected 31

Microcopy chart designed 31

Method developed for measuring thiosulfate in processed film . . 32

Length measurement research 32

Thermal expansion measurement capability extended 32

Wave-front-shearing interferometer * 32

Screw thread standardization 33

Laser produces fringes over 200-meter path 33

Cockpit lighting in TFX aircraft 33

Accuracy of spectral transmittance standards investigated ... 33

Goniophotometry 34

2.1.2. Mechanics 34

Vibration amplitudes measured 35

Microphone calibration 35

Portable tube designed for sound-absorption measurements. ... 35

Cavitation data obtained 36

Measurement of impact sound transmission in buildings 36

Infrasonic waves studied in the atmosphere and in the earth ... 36

Audiometry research 38

Improvements sought in pressure and vacuum measurements . . 38

Computer techniques applied in turbulence studies 39

Boundary layer instability and effect of roughness 39

Standards designed for million-pound forces 40

Compact precision centrifuge constructed 41

Rheological constitutive equations 41

Review of volume relaxations in polymers 41

Hypersonic combustion 42

Reference fuel control test facilities operated at the Bureau .... 42

Static electric failure of aircraft engine fuel hose 43

Reference tables for a new thermocouple to be established. ... 43

Flame speed inhibitors 44

High-temperature thermocouples 44

III

Highlights of the research program — Continued

2.1. Physics, electronics, and measurement standards — Continued Page

2.1.3. Electricity 44

Absolute measurements 44

Impedance of dry cells 45

Battery depolarizers at high temperatures 46

Zener diodes as voltage standards 46

Membrane potentials in fused salts 46

Differential a-c-d-c transfer standard 47

Magnetism 47

Dielectric behavior of liquids and supercooled liquids at ele-
vated pressures 48

Precision measurement of the dielectric constant of solid bodies . 49

Humidity-time studies of dielectric constant and loss index. ... 49

Theoretical studies on dielectrics 50

Chain-folding in polymer crystals 50

Dielectric properties of polymers 50

Dielectric properties of dipolar chain compounds 50

Microwave absorption in compressed gases 51

High voltage 52

2.1.4. Radio standards 52

Theoretical physics 53

Radio standards physics 53

Fort Collins standard radio transmitting site 53

Atomic frequency standard research 54

Quantum electronics 55

Radio and microwave materials 56

Magnetics 56

Dielectrics 57

Conductivity 57

Materials synthesis 57

Plasma 57

Microwave interactions with plasma 58

Speed of light (diffraction correction) 58

Stark voltmeter 59

Radio standards engineering 59

Low-frequency calibration 59

High-frequency standards and calibration 60

Microwave standards and calibration 62

Fabry-Periot interferometer used as a dilatometer 64

2.1.5. Heat 65

Molecular energy levels program 65

Plasma transport processes 66

Automatic thermocouple comparator 66

Thermodynamic properties of light-element compounds 67

Computer analysis of low-temperature heat-capacity data. ... 68

Thermal diffusivity standards 69

Microwave spectroscopy 69

Nuclear orientation 69

Shock wave reaction kinetics 69

Thermodynamic properties of gases at high temperature 70

2.1.6. Atomic physics 71

Continuum states in rare gases 71

Plasma and astrophysics 74

Atomic energy levels . 74

Wavelength standards 75

Infrared spectroscopy of gases 75

Shapes of rotational lines as influenced by pressure 76

Absorption spectra of solids 76

Solid state physics 76

Electron optics 77

Measuring velocity of light

Optical pumping 77

Magnetic moment of the proton 78

Experimental atomic collisions 78

2.1.7. Radiation physics 78

X-ray and gamma-ray dosimetry 79

Cavity chambers 79

Photographic dosimetry 79

Solid state dosimetry 79

Highlights of the research program — Continued

2.1. Physics, electronics, and measurement standards — Continued
2.1.7. Radiation physics — Continued

Response of silicon charged particle detectors at low temper- Page

atures 80

Radioactive sources 80

Scattered spectrum of water-shielded sources 80

Standards of radioactivity 80

Radiation interaction with matter 82

Radiation interaction with nuclei 82

The interaction of bremsstrahlung with alined nuclei 82

Nuclear matter distributions as determined from neutral

meson photoproduction 82

Neutron time-of-flight techniques . 84

Particle interaction theory 85

Preparations for new linear accelerator 85

Linear accelerator theory 85

Heavy-ion source for magnet-optic studies 86

High-current beam-handling problems 86

Equipment for use with Linac 86

Data-logging and data-handling system for the linear

accelerator 86

2.1.8. Laboratory astrophysics 87

Physics of atomic collisions 88

Astrophysics 89

Resonance physics 89

Plasma physics, statistical physics, and aerodynamics 90

Data center on atomic collision cross sections 90

2.2. Chemistry and properties of materials 90

2.2.1. Analytical and inorganic chemistry 90

Atomic weight redetermination 91

Reactivity of coordination compounds 91

Thermodynamics of aqueous solutions 91

pH scale for alcohol-water solvents 91

Dielectric cryometry for determining purity 92

Argon shielding in spectrochemical analysis 92

Transition probabilities 93

Laser microprobe 93

Solvent effects on the rates of acid-catalyzed reactions 94

Acidities of dinitrophenols in benzene and water 94

Crystal growth from mixed solvents 94

Studies of crystal symmetry 95

X-ray analysis of crystalline solids 95

Control of fractional distillation 96

Moisture determination 96

2.2.2. Physical chemistry 96

Thermochemistry 97

Kinetics of ion decomposition 97

Field emission , 97

High-temperature microwave spectroscopy 97

Enolization and isomerization reactions of reducing sugars ... 98

Cryogenic surface chemistry 99

Kinetic isotope effects 99

Shock-wave studies of unimolecular reactions - 99

Ionization processes at surfaces 100

Polycyclic ketones 100

Vacuum ultraviolet photochemistry 101

High-temperature surface reactions 101

Radiolysis of simple hydrocarbons 101

Standard reference data in physical chemistry 102

2.2.3. Inorganic solids 102

Rare gas crystals 102

Molar volume of solid neon isotopes 103

Crystalline forms of bismuth oxide 103

Random network models for liquid and glass studies 104

Vapor-pressure studies 105

Crystal structure determinations 105

Phase change studies of silica-metal oxide systems 105

Standard glasses for viscosity measurements 106

Elastic constant data 106

Highlights of the research program — Continued

2.2. Chemistry and properties of materials — Continued

2.2.3. Inorganic solids — Continued Page

Structural studies of materials under high pressures 106

Mechanical properties of ceramic bodies 108

2.2.4. Metallurgy 108

Metal fatigue investigated in aluminum alloys 109

Properties of metals at elevated temperatures 109

Gage block materials demonstrate desired stability 110

Deformation of metals studied at low temperatures 110

Slack-quenching technique developed 110

Stress corrosion of carbon steels Ill

Effect of applied current on aluminum corrosion Ill

Corrosion reactions studied at metal surfaces Ill

Pure alloys prepared Ill

Standard samples Ill

Equilibrium diagrams developed 112

Experimental alloy demonstrates usefulness 112

Steel pilings inspected 112

Correlation effects for impurity diffusion 112

Electron microanalysis provides basic data 112

Quantitative metallography derived with computer 112

Anisotropic effects studied in a cubic alloy 113

X-ray diffraction employed for crystal structure studies. ... 113

Dislocations in metals investigated 113

Kinetics of whisker growth and evaporation . . . 113

Properties of electrodeposited copper 114

Electrocrystallization investigated 115

Calorimetry used to study fused salts 115

Peltier effect measured at liquid junctions 115

Cooperative services provided 115

2.2.5. Polymers 116

Ethylene-propylene copolymers analyzed 116

Bitumen content in expansion joint fillers readily determined. . 117

Tensile properties of paper 117

Tongue-tear methods for woven fabrics evaluated 117

Color tests devised for antioxidants in synthetic rubbers 118

Point-projection X-ray microscopy used to study polymers. ... 118

Leather macroporous structure investigated 119

Structural transformations observed in polymers at high pres-
sures 119

Phase equilibria in polymer solutions 119

Statistical calculations made of polymer properties 120

Rubber crystallization investigated 120

Failure phenomena of fibers studied at high impact velocities. . 120

Radiation-induced polymerization under high pressure 122

Fluoroaromatic polymers prepared 123

High-energy radiation effects on polymers 123

Thermal stability of coordination polymers investigated 124

Stereoregular polyacenaphthylene produced 124

Polymer adsorption 124

Molecular weight standards for polystyrene 124

Structure and strength of teeth 125

X-ray spectrometer used for analysis of dental alloys 125

Dental cements 126

2.3. Special technical service programs 126

2.3.1. Applied mathematics 126

Numerical analysis 126

Asymptotic expansions 127

Quadrature and interpolation 127

Linear algebra and matrix theory 127

Machine translation 127

Mathematical tables 128

Digital computations 128

Statistical engineering 128

Research and development 129

Experiment design and consultation 129

Mathematical physics 130

Plasma research 130

Theory of satellite orbits 130

2. Highlights of the research program — Continued
2.3. Special technical service programs — Continued

2.3.1. Applied mathematics — Continued Page

Operations research 130

New computer facilities at Boulder Laboratories 131

Mathematics group at Boulder Laboratories 131

Statistical studies at Boulder Laboratories 131

2.3.2. Data-processing" systems 132

Research information center 132

Components and techniques 133

Scientific information processing 134

Technical assistance for data processing 135

Information-processing systems 136

Engineering applications and devices . . .' 138

Special studies and analyses 138

Management data processing 140

Automatic mail-sorting developments 140

2.3.3. Instrumentation 141

Failure anticipation by semi-automatic techniques 141

Hall effect measurements 142

Vacuum physics 142

A photoelectric ratio-measuring system for incident light 143

Proportional temperature controllers 143

Hygrometry 144

Electromechanical transducers 145

Instrument reference service 145

2.3.4. Radio propagation 146

IQSY 146

Ionosphere research and propagation 146

Geomagnetic micropulsations and infrasonic pressure waves . 146

Lunar tide effect in the Z>-region 147

Effect of VLF propagation on standard frequency trans-
missions 147

Ionizing processes in the Z)-region of the ionosphere 148

Ionospheric predictions by numerical mapping 148

First topside sounder satellite 149

Planetary ionosphere 150

Assistance to Project Mercury 150

Ionospheric ray tracing 151

Operation Fish Bowl 151

Thermal properties of the jF-region 152

Chemical release in the ionosphere 152

Electron density measurements in the ionosphere 153

Troposphere and space telecommunications 153

Reports to the CCIR 153

Prediction methods 154

Electromagnetic theory 154

Point-to-point moon communication 154

Radio meteorology 154

Efficient television assignments 155

UHF air-ground propagation tests 155

Refractive effects in microwave distance and position

measurement systems 156

Surface-satellite communication interference 156

Bandwidth of the tropospheric propagation medium 156

Radio noise predictions 158

Floating noise recordings 158

Automatic data analysis facility 159

Radio systems 159

High-frequency ionospheric radar research 159

Solar flares 161

Modulation research 161

Digital errors 162

Testing facsimile equipment 162

Recording atmospheric noise 162

Multipath microwave transmission 163

Antenna measurements and research 163

Computer program for radiation patterns 163

Frequency utilization 164

Radio navigation research — low-frequency Loran 165

VII

2. Highlights of the research program — Continued
2.3. Special technical service programs — Continued

2.3.4. Radio propagation — Continued

Radio Systems — Continued

Applied electromagnetic theory at frequencies below 300 Page

kc/s ; 166

Optical communication studies 167

Upper atmosphere and space physics 167

Jicamarca Radar Observatory 167

Digital control and correlation system for the Jicamarca

Radar Observatory 169

Studies at magnetically conjugate points 170

Continuous observations of VLF emissions 170

VLF emissions and whistlers at conjugate points 170

Electron densities in the lower ionosphere 171

Auroral absorption 171

Absolute calibration of airglow photometers 172

Mid-latitude red arcs 172

Studies of ionospheric irregularities 1 72

Theoretical studies of the outermost atmosphere 173

Cyclotron resonance in slightly ionized gases 174

Space resolved afterglows 174

Infrared spectra of charge transfer complexes 174

Infrared spectroscopy of the atmosphere 175

Electromagnetic research 175

Resonant characteristics of a corrugated sphere 175

Influence of a sector ground screen on the field of a vertical

antenna 176

The theory of an antenna over an inhomogeneous ground

plane 176

Curves for groundwave propagation over mixed land and

sea paths 176

Wave propagation around a curved boundary containing

an obstacle 176

Oblique propagation of radio waves across a coastline 176

Guided electromagnetic waves in the earth's crust 177

Electromagnetic scattering from a sphere 177

VLF radio propagation in an anisotropic ionosphere 177

Excitation of modes at very low frequency 177

Height-gain for VLF radio waves 177

Characteristics of an inhomogeneous D-layer at VLF 178

Propagation in a nonuniform earth-ionosphere waveguide. . 178

Microwave models for VLF propagation 178

Theory of magnetotelluric fields 179

2.3.5. Cryogenic engineering 179

Dielectric behavior of dense parahydrogen 179

Superconductivity 180

Magnetic properties in silicon steel 181

Low-temperature seals 181

Cryogenic literature service 181

Thermophysical properties of cryogenic materials 182

Fluid flow and heat transfer phenomena 182

Cryogenic instrumentation 183

Cryopropellant research 184

Refrigeration processes 185

Consultation and advisory services 185

Liquefied and purified gases 186

2.3.6. Building research 186

Building codes and safety standards 187

Creep and shrinkage of structural lightweight concretes 187

Joint sealants for building components 188

Waterproofing underground structures 188

Colloidal nature of asphalts 189

Photooxidation products in plastics identified 189

Fluid dynamics of plumbing 189

Test methods for air-conditioning units 189

Test methods for refrigerated trucks 190

Criteria for heating and air-conditioning ducts 190

Thermal emittance of ceramic oxides 190

Automation of thermal emittance measurements 191

VIII

2. Highlights of the research program — Continued
2.3. Special technical service programs — Continued

2.3.6. Building research- — Continued Page

Thermal conductivity reference materials 191

Thermal conductivity measurements by radial heat flow 192

Performance specification for insulated flat-roof constructions. . 192

Heat of hydration of portland cement 192

Electron capture of combustion inhibitors 193

Surface flame propagation 193

Fire research contracts 193

2.3.7. Weights and measures 194

3. Appendixes , . 197

3.1. Organization 197

3.2. Summary of NBS staff „ 203

3.3. Financial data on NBS program 204

3.4. Advisory committees 204

3.5. Awards and honors . . .* 209

3.6. Education and training program 210

3.7. List of publications and patents 212

1. GENERAL REVIEW

During the past year the National Bureau of Standards continued efforts
to focus and strengthen its technical program in support of the Nation's
technological advancement and economic growth. Major areas of effort
were basic measurement standards, standard reference data, engineering
measurement standards, standard reference materials, radio propagation,
data-processing systems, and building research.

In this program the Bureau was concerned primarily with research and
technical services in the general field of physical measurement — a field of
basic importance to progress in commerce, industry, and science. Commerce
involves exchange of goods and services, and standards of physical measure-
ment provide a basis for determining both quantity and quality in com-
mercial exchange. Similarly, progress in science and in the application of
science to technology is based on the exchange of information, particularly
quantitative data, derived by the use of measurement standards. Thus, the
Bureau strives to advance measurement science and to further its application
in order to facilitate the reliable, efficient exchange of quantitative data in
science and engineering and of technological products and services in
commerce.

Within the field of physical measurement, the Bureau is concerned with
four distinct but related types of standards: (1) Standards for the physical
quantities and units basic to the physical sciences and engineering; (2)
standards for the determination of quantity, quality, or performance of the
technological products and materials of commerce; (3) standard reference
data; and (4) standard reference materials for use in controlling chemical
processes and maintaining the accuracy of apparatus and equipment.

Through the years, in order to meet specific needs of the Government,
the Bureau has also undertaken responsibility within Government for oper-
ating central research and technical service programs in special areas. Such
programs are carried on by the Central Radio Propagation Laboratory, the
Data Processing Systems Laboratory, and the Building Research Division.

In addition to the above mission-oriented activities, the Bureau conducts
a broad program of exploratory or background research in the physical
sciences. The primary purpose of this work is to maintain and strengthen
the general scientific competence of the Bureau staff so that the Bureau can
keep abreast of new developments in many fields, select the most effective
techniques for solving problems, and utilize quickly the results of scientific
work elsewhere. At the same time, however, the results of this research may
be expected to contribute substantially to the Nation's scientific progress.

This report attempts to present the highlights of the Bureau's program
for the fiscal year 1963. In Section 2, the body of the report, studies and
achievements from the various fields in which the Bureau is active have been
selected for brief presentation. However, the breadth of the program and
diversity of projects may make it difficult for the reader to obtain a coherent
picture of the year's activity. The remainder of Section 1 is therefore de-
voted to a brief summary of the more important accomplishments and
activities of the year.

BASIC MEASUREMENT STANDARDS

The National Bureau of Standards is responsible for developing and
maintaining the national standards of physical measurement upon which all
measurements in this country are based. As part of its measurement re-
sponsibility, the Bureau must also see that these standards are made available
to science, industry, and commerce through suitable calibration services.

During the last year the Bureau continued to be faced with the demands
of a rapidly expanding technology for greater accuracy and range in the
calibration services provided to laboratory, plant, and shop. A consider-
able portion of the research effort was therefore directed toward the exten-
sion of precise standards and measurement techniques to new areas of
science and technology, and to new accuracies. Services added during the
year included calibration of microwave noise sources, at 9.0, 9.8, and 11.0
Gc/s, and power calibration of bolometer and bolometer-coupler units.

Insofar as possible, the Bureau restricted its own calibration work to
master standards and high-precision instruments, leaving the calibration of
lower-echelon standards to the other standards laboratories that have been
set up by industry and the military services. Even so, the volume of NBS
calibration services continued at a high level (table 1). Over 75,000 cali-
brations, having a total value of more than $2 million, were performed for
Government and industry.

In an effort to cope more effectively with the calibration load, further
efforts were made to automate calibration procedures so that the output
data appear directly on punched cards or tape, ready for computer reduc-
tion. Two devices for this purpose were developed during the year: an
automatic thermocouple comparator and a data-recording assembly for
measurement of thermal emittance standards.

For several years the Bureau has been conducting a research program
looking toward the development of procedures for calibrating master gage
blocks on a regular basis to 1 part in 10 million. This work was begun,
at the request of machine tool manufacturers, in order to meet the stringent
calibration requirements imposed by the use of increasingly smaller toler-
ances in industry. Attainment of the program's objective requires develop-
ment of both highly stable gage blocks and ultra-precise measuring tech-
niques. Two types of gage blocks have now been developed which are
dimensionally stable to better than one 10-millionth of an inch per year, and
seven additional types have been produced which are stable to between one

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and two 10-millionths of an inch per year. In the measurement part of the
program, an investigation was begun to determine the thickness of the
molecular film between joined gage blocks, which in practice must be con-
sidered as a part of the length of the blocks. In support of this research,
theory was developed which provided new knowledge about the behavior
of light beyond a surface normally thought to be totally reflective.

In research to develop more accurate methods of measuring long dis-
tances, promising results were obtained through use of a helium-neon laser
as the infrared light source for a Michelson interferometer. With this
apparatus, interference fringes — normally visible over an optical path of
not more than 2 meters — were obtained over an optical path of approxi-
mately 200 meters. Thus use of a gaseous laser source appears to offer a
means for measuring long distances to high accuracy. Work is now under-
way to stabilize the laser equipment so that interferometric calibrations of
length-measuring devices may be made with the laser.

The accurate measurement of spectral irradiance has assumed increasing
importance in connection with studies of the irradiance to which space
vehicles will be subjected. During the year a new standard of spectral
irradiance was developed in the form of a 200-watt quartz-iodine lamp with
a coiled tungsten filament operating at about 3000 °K. The new standard
operates without auxiliary optics and provides relatively high spectral
irradiances.

Progress was made in research efforts seeking to develop standards and
measurement techniques for very high pressures. For use as a fixed point
in calibration work, the freezing pressure of mercury at 0 °C was deter-
mined to be 109,722 lb/in.2, accurate to within ±30 lb/in.2. A new piston
gage was under construction for use in a more accurate determination of
the phase transition of bismuth between 365,000 and 370,000 lb/in.2. This
transition has been serving as the principal calibration point in the ultra-
high-pressure range.

A number of advances were made in the field of electrical measurement.
For example, a new differential a-c-d-c transfer standard was developed to
meet the growing need for greater speed and accuracy in measuring a-c
voltages at audiofrequencies. Unlike older forms of a-c-d-c transfer instru-
ments, in which successive comparisons were required, this instrument can
be used for the simultaneous comparison of an unknown a-c voltage with a
known d-c voltage. It provides a usable precision of 10 parts per million.

A permanent adjustable standard of magnetic susceptibility was designed
and was incorporated into a magnetic susceptibility bridge of high accuracy
and sensitivity. Other apparatus was constructed for determining absolute
magnetic susceptibilities down to liquid helium temperatures.

A microwave phase-shift measuring system was developed that is capable
of measuring phase shift to an accuracy within 0.01 degree. The system
is now ready for use in a national microwave phase-shift calibration service.

Research continued on atomic standards of frequency and time. The
United States Frequency Standard, which is derived from a natural fre-

quency of the cesium atom, is now accurate to better than one second in
3,000 years. During the year one of the two cesium beam frequency stand-
ards that have been used in maintaining the national standard was converted
to a thallium beam for the purpose of evaluating a thallium transition as
the standard of frequency, and it appears that an improvement of one order
of magnitude in accuracy over that of cesium can be expected. Also, a new
cesium beam frequency standard was completed which promises to have a
precision about twice that of the other cesium standard now in use. The
United States Frequency Standard provided a basis for the establishment
of an NBS atomic time scale. The NBS atomic time was related to the time
pulses of NBS radio station WWV, to the atomic time kept by the Naval
Observatory, and to the time pulses of the Loran-C master station at Cape
Fear,N.C.

The Bureau continued to cooperate closely with the National Conference
of Standards Laboratories. This Conference and its continuing committees
bring together representatives from military, industrial, and university stand-
ards laboratories, to promote cooperative action on common problems of
the management and operation of measurement standards and calibration
laboratories. In August 1962 the Bureau was host to the first national
meeting of this organization at the NBS Boulder Laboratories. Over 600
persons attended the Conference, the proceedings of which were published
by the Bureau.

The Bureau also cooperated in an interservice measurement audit which
is designed to promote measurement agreement among the military- services.
Items being measured include resistance and capacitance standards, a fre-
quency meter, an optical polygon, and a vibration pickup. Results of tests
on these items by the Bureau, the Army, Navy, Air Force, and Sandia
Corporation representing the Atomic Energy Commission, will be analyzed
by the Air Force.

A series of precision measurement seminars, designed to provide an op-
portunity for qualified senior people from other organizations to benefit
from the Bureau's long experience in certain measurement areas, was an-
nounced during the year. Attendance at these seminars, in the fields of
length, acoustics, frequency comparison techniques, attenuation at communi-
cations frequencies, and precision and accuracy, was limited to permit de-
tailed individual participation. Registrants were selected from Government,
industry, and university laboratories.

During the year a uniform format for reporting the results of calibrations
and tests was adopted. All such results are now issued in report form, sup-
plemented by a letter of formal certification when required by law or special
conditions. Generally the reports include more useful discussion and evalu-
ation of the uncertainties involved than was formerly provided.

The preparation of charts showing NBS capabilities in various measure-
ment areas was continued. Several of these charts are reproduced on
page 6.

ONE

par r

ACCURACY OF LENGTH MEASUREMENTS AT NATIONAL BUREAU OF STANDARDS, 1962
EXISTING CAPABILITIES OBJECT OF EXISTING PROJECTS

E LIGHT WAVELENGTH, USING INTERFEROMETER IN AMBIENT ATMOSPHERE

10'

•- I05

3 io4

10'

GAGE
CALIBRATION

END
STANDARD

FRUSTRATED
REFLECTION

'l llllllll I IMIIll/l lllhll I linilll I llllllll I llllllll il I 1 1 mill l i. mi' i iiiiiiiI i iniiiil i

10 10

i66

10 10

io3

10 10

LENGTH, INCH

10 10 10 10

10 10 10

LENGTH.METER

10 10

ppm

io"12 io"10

10" 10" 10 10

CAPACITANCE IN MICROFARADS

Charts depicting NBS capabilities in the measurement of length (top) and ca-
pacitance (bottom).

STANDARD REFERENCE DATA

During 1963 a considerable portion of the Bureau's research effort was
devoted to the development of standard reference data in the physical sci-
ences. In addition a number of data centers for compilation and storage
of critically evaluated data were operated in such areas as chemical thermo-
dynamics, atomic transition probabilities, atomic cross sections, ceramic
phase equilibria, and cryogenics. During the year, the Data Center on
Atomic Collision Cross Sections completed a survey of all literature reporting
cross sections for two-body collisions involving a free electron. This Center
is now providing bibliographic searches for the general scientific community
and is preparing a complete bibliography by subject classification. The
Data Center on Atomic Transition Probabilities published a bibliography
containing a complete listing of pertinent articles in this field and had almost
completed a critical evaluation of transition probability data on the first
10 elements.

The Cryogenic Engineering Data Center continued to serve as a clearing
house for research and development literature on cryogenics. During the
year some 4100 new references were coded and entered into the Center's
storage and retrieval system. Special attention was given to low-temperature
data on the properties of solids and fluids; 1500 of the new entries were
in these categories. A number of extensive bibliographies on properties of
materials were compiled, and an estimated 20,000 items of NBS literature
were distributed in response to some 1500 requests.

An important area of research was concerned with the application of the
wall-stabilized arc for the measurement of transition probabilities and to
gain a better understanding of high-temperature plasma phenomena. The
shifts and widths of several oxygen lines were measured and the results were
found to be in good agreement with recent theories on line broadening in
dense plasmas.

In other studies using a gas-stabilized arc, transition probabilities for
105 lines in the spectrum of neutral atomic iron were redetermined to higher
precision than in previous work.

Apparatus was constructed to study the variation in dielectric constant
and relaxation time for liquids and supercooled liquids at pressures up
2000 atmospheres and at temperatures from liquid nitrogen temperature
( — 196 °C) to about 50 °C. By suitable choices of temperature and pres-
sure, measurements with this apparatus may be conducted at constant density
in order to provide more definitive tests of dielectric theory.

A microwave spectrometer which can be operated at temperatures up to
1000 °C was constructed and applied successfully to several problems in
high-temperature chemistry. This instrument permits the extension of pow-
erful microwave techniques to the identification and structure determination
of molecules and radicals that are present in high-temperature systems.
Spectra for such molecules as aluminum monofluoride and aluminum mono-
chloride, which do not exist at room temperature but which are important
constituents in rocket combustion systems, have been detected and analyzed.

714-691 0—64 2 7

New information on the atomic energy levels of the rare gases helium,
neon, and argon was obtained in a series of independent experiments which
utilized both electron and photon interactions. Optical photons in the far
ultraviolet, produced by the accelerated electrons in the Bureau's 180-Mev
synchrotron, were used in studies of the absorption properties of the three
gases, which resulted in the discovery of a number of new atomic energy
levels in these gases. These findings were confirmed in observations on
energy losses of electrons scattered by the gases and in theoretical studies
of their ultraviolet absorption properties.

Determination of the structure of carbon suboxide (C302) resolved a
scientific controversy of 30 years' standing. Through analysis of a high-
resolution infrared absorption spectrum, conclusive evidence was obtained
that the molecule is a straight chain consisting of three carbon atoms with an
oxygen atom at each end. Since 1933, when the carbon suboxide molecule
was reported to have a dipole moment, indicating some sort of bent struc-
ture, molecular spectroscopists have been divided in support of linear and
nonlinear configurations. Valence theory predicts the linear form, but
earlier studies, handicapped by inadequate resolution and impure samples,
provided inconclusive and contradictory results. Finally, the Bureau ob-
tained new evidence by using ultra-high-resolution techniques to determine
the rotational fine structure of a band in the 3-micron region.

National Standard Reference Data System. In June 1963, the Office
of Science and Technology, acting on a recommendation of the Federal
Council for Science and Technology, established a National Standard Ref-
erence Data System (NSRDS) to provide critically evaluated data in the
physical sciences on a national basis. The Bureau was given responsibility
for administering the System, which will centralize a large part of the present
data-compiling activities of a number of Government agencies.

The aim of the NSRDS is to develop a storehouse of standard reference
data to assist in the advancement of science, technology, and the national
economy. This result is to be achieved through a broad-based, comprehen-
sive effort by scientists both in and outside the Government.

The Bureau, as well as other organizations in this country and abroad,
has been active in the compilation of standard reference data for many years.
However, in view of the great accumulation of unevaluated data over the past
few years, the present accelerated production of new data, and the urgent
needs of American science and industry, it has become apparent that a sub-
stantially greater effort, planned and coordinated on a national basis, is
needed.

The National Standard Reference Data System will consist of a National
Standard Reference Data Center at the Bureau, and various other Standard
Reference Data Centers in other Government agencies and at universities,
research institutes, and other non-Government organizations. In order for
such centers to be a part of the NSRDS, they will be required to meet quality
standards established by the Bureau. However, the independent and opera-
tional status of existing critical data projects will be encouraged.

An Advisory Board will review and recommend policy relative to the
operation of the NSRDS. It will include, among others, representation
from the National Academy of Sciences, National Science Foundation, and
Federal agencies engaged in research and development.

The NSRDS will be conducted as a decentralized operation across the
country, with central coordination by the Bureau. According to present
plans, the data input will come from scientists in many different locations
who will comprehensively review the literature in their fields of specializa-
tion and will critically evaluate the data it contains. The evaluated data will
be classified and stored at the Bureau and will be disseminated through a
series of services tailored to user needs in science and industry. In choosing
work to be undertaken, the Bureau will be assisted by the Advisory Board,
interagency panels, expert consultants in the subject-matter areas, and work-
ing committees of the scientific and engineering societies and industry asso-
ciations that are active in the field of critical data.

ENGINEERING MEASUREMENT STANDARDS

The Bureau cooperates extensively with recognized standardizing bodies
in the development of codes, specifications, standards of practice, and meth-
ods of test for technological devices, products, and services. In general, the
Bureau contributes by conducting research to provide test methods, data on
materials, and measurement standards; the sponsoring organization supplies
other technical data and promulgates the finished documents in the form of
codes, specifications, or engineering standards. The Bureau is in a position
to provide material assistance in this field because of the active participation
of its staff members in the work of numerous technical societies and stand-
ardization groups such as the American Standards Association, the American
Society for Testing and Materials, and the Society of the Plastics Industry.

The Bureau also plays an active role in the development of government
purchase specifications. During fiscal 1963, at the request of the General
Services Administration, the Bureau accepted responsibility for preparing
and maintaining two additional Federal Specifications, making a total of
154 for which it now has this responsibility. The Bureau also reviewed
approximately 600 proposed specifications both for GSA and for other
agencies to determine their suitability for use by the Federal Government.

In June 1963, the scope of the Bureau's program in technological stand-
ards was increased with the transfer of the Commodity Standards Division
of the Office of Technical Services, U.S. Department of Commerce, to the
National Bureau of Standards. The transferred activity provides assistance
to industry, business, and consumers in the development and acceptance of
voluntary trade standards that define quality levels for products and aid in
holding variety to a minimum.

In the last year, many experimental data were obtained for developing
and improving building codes, standards for building materials, and methods
of testing building materials and equipment. Typical of this work were
investigations of the creep and shrinkage of structural lightweight concrete,

studies of methods of waterproofing underground structures, and work to
extend methods of measuring thermal emittance and thermal conductivity
to higher temperatures.

Fiberglass-reinforced plastics are being employed for many structural
purposes today. However, weather exposure decreases their strength and
light-transmitting characteristics. During 1963 the Bureau developed a
sensitive colorimetric method for determining degradation of fiberglass-
reinforced polyester plastics. This method provides a rapid, reproducible
means for predicting durability.

Laboratory investigations leading to the development of a testing and
rating method for refrigerated trucks were carried out under the joint spon-
sorship of the U.S. Department of Agriculture, the Truck Body and Equip-
ment Association, and the Bureau. An apparatus for simulating the effect
of solar radiation on the cooling load of stationary refrigerated trucks was
designed and constructed. It was found that the air and moisture trans-
mission through the body was significantly different for different construc-
tions, and that the effect of solar radiation could be satisfactorily accounted
for by a correction factor to the steady state heat transfer.

In other research for development of test methods, a technique was de-
vised for using a digital computer to analyze the microstructure of metals
and alloys. This computer technique takes the place of tedious manual
operations in determining the size, shape, and number of crystals or grains
found in photomicrographs of metal or alloy structures. In this way analyses
are accomplished up to a thousand times more quickly than has been possible
with conventional manual methods. Thus far the technique has been used
in studies of the graphite content of cast iron and of niobium-tin phases in
experimental superconductor alloys. The rapid, accurate results obtained
in these studies demonstrate the feasibility of employing computer programs
in micrographic analyses, and suggest the use of the technique in other areas,
such as petrography, microbiology, astronomy, and photogrammetry.

A new three-terminal dielectric cell was completed and used to make pre-
cise dielectric constant measurements by the two-fluid method which requires
no electrodes. With this apparatus the dielectric constant of a disk specimen
can be obtained to within better than 200 parts per million between 100
cycles per second and 50 kilocycles per second.

A scheme of color tests was developed for identifying the five antioxidants
commonly used in styrene-butadiene synthetic rubbers. These antioxidants
include naphthylamine and diphenylamine compounds, styrenated phenols,
and alkylated arylphosphites. By using specified successive tests involving
two or more of a group of 12 reagents, the uncertainty of distinguishing
between similar colors obtained with a single test was overcome.

An improved analytical procedure was developed for measuring the thio-
sulfate radical remaining in photographic film after processing. Such tests
are routinely conducted to assure conformance to microfilming specifications.
The new procedure reveals two or three times as much residual thiosulfate

as does the current standard analytical method which has been in use for the
past 30 years.

During fiscal year 1963, the Bureau tested 53,877 items ranging from
dry cells to building materials (table 2). Most of the tests were on items
purchased by other Federal agencies that lacked the facilities to make the
tests themselves.

STANDARD REFERENCE MATERIALS

During fiscal year 1963 the Bureau distributed 72,074 samples of standard
materials, having a value of $551,264, to other laboratories (table 3).
Nearly 600 different standard materials are at present available — principally
chemicals, ceramics, metals, and radioactive nuclides. New standard mate-
rials added during the year included radioactivity standards of iodine 125
and cerium 139; two polystyrene molecular weight standards; five portland
cement standards; a standard soda-lime-silica glass; and various alloys for
spectroscopic standardization. All are certified either for chemical com-
position or with respect to a specific physical or chemical property such as
melting point, viscosity, or color.

In research to develop new standard materials, a technique known as
dielectric cryometry was devised for precise determinations of purity. In

A new method of producing glass with controlled light scattering properties led
to these prototype turbidity standards. They are now being studied as possible
replacements for the less durable plastic and liquid standards presently in use.
(See p. 11.)

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this method, measurements of the change in dielectric constants are used to
determine the solid-liquid ratios corresponding to various freezing (or melt-
ing) temperatures of the substance studied. An advantage of the method
is that it permits use of relatively small samples (4 to 10 ml) to determine
purity.

In studies of phase changes in silica-metal oxide systems, a means was
found for producing glasses having a controllable degree of light scattering.
Glasses of this type are being evaluated as turbidity standards to replace the
less durable plastic and liquid standards that are now in use.

Because of its reproducibility, the pH of solutions in alcohol-water solvents,
determined with commercial electrometric pH equipment, is an important
control variable in certain research operations as well as in industry and
commerce. Until recently, however, pH numbers determined in the conven-
tional way could be interpreted in terms of hydrogen ion concentration or
activity only when the solvent medium was pure water. During 1963, a scale
of pH (designated pH*) for methanol-water and ethanol- water media was
shown to be practical, and procedures were devised for assigning standard
values of pH* to reference solutions. The pH* determined experimentally
bears a simple relation to dissociation constants and other thermodynamic
quantities in the same medium and, as such, should have wide application
in many branches of chemistry and biology.

SPECIAL CENTRAL MISSIONS

Radio Propagation, Within the Federal Government, the NBS Cen-
tral Radio Propagation Laboratory (CRPL) has been given the central re-
sponsibility for collecting, analyzing, and disseminating information on the
propagation of radio waves at all frequencies along the surface of the earth,
through the atmosphere, and in outer space. To carry out this responsibility,
it conducts research on the nature of the waves, the media through which
they are transmitted, and the interaction of the waves with the media.

During 1963, ground-based studies of the ionosphere in the vicinity of the
earth's equator were made by a scatter radar technique at the Jicamarca
(Peru) Observatory of CRPL and of the Instituto Geofisico de Huancayo
(Peru). This observatory, located on the magnetic equator near Lima,
employs a 6-million-watt transmitter and a 22-acre antenna to transmit a
very-high-frequency radio wave of extremely short duration to great heights.
The antenna is also used to detect the faint reradiation of the pulsed radio
wave by free electrons in the upper atmosphere. The primary function of
the installation is to study the distribution of electron density with height
out to 6,000 miles or more above the earth's surface.

In cooperation with the Instituto Geofisico de Huancayo, the Jicamarca
Observatory made a series of measurements of the synchrotron radiation
that was emitted by the manmade belt of high-energy electrons which formed
as a result of the high-altitude nuclear detonation occurring above Johnston

Island in the Pacific on July 9, 1962. From these measurements, made at
30 and 50 megacycles per second, the number, energy spectrum, and decay
rate of the electrons were derived — information that will help improve under-
standing of the physics of the upper atmosphere. The extremely high radar
sensitivity available at Jicamarca also made possible the detection of radar
echoes from Venus when the planet was observable from Lima during the
first week of December 1962.

Data-Processing Systems. In the rapidly advancing field of auto-
matic data processing, the Bureau serves the Federal Government as a center
for research and services to promote more effective utilization of data-
processing facilities within the Government. With the increasing variety
and complexity of governmental applications of data processing, the scope
of the research program in this field has correspondingly increased until it
now utilizes the techniques of several scientific disciplines. Representative
activities during the past year included exploration of the operational char-
acteristics of new components to determine their suitability for computer
circuitry, studies of the properties of materials used in new components, and
development of techniques for extending automated procedures in areas such
as the processing of scientific information. Studies were conducted on ultra-
thin ferromagnetic films as potential high-speed random access memory ele-
ments, and an investigation was begun of the technique of quantitative
analysis of thin films by X-ray fluorescence. Research continued on simula-
tion and characterization of semiconductor devices such as tunnel diodes
and epitaxial transistors. In connection with this work, a counter circuit
incorporating tunnel diode-transistor type of circuitry was developed that
is capable of counting up to 80 megapulses.

Building Research. Studies were conducted in physics, chemistry,
and engineering to develop new knowledge relating to building materials,
equipment, and structures. For example, work was done on the reactions
which take place in concrete upon setting, involving heats of formation of
many compounds, and on the reactions which take place after setting, in-
volving the corrosion of concrete reinforcements. Other typical investiga-
tions dealt with methods of controlling unwanted fires, heat transfer in
structures, mechanical systems for buildings, metallic building materials, and
properties of asphalts. During the year, experimental results were obtained
which support the colloidal theory of asphalt: the presence of an electric
charge on dispersed asphalt particles was detected and measured. Although
the theory of the colloidal nature of asphalts has received wide support since
its proposal many years ago, until this finding little if any experimental evi-
dence to support the theory had been reported.

CONSULTING SERVICES

To a considerable extent, the Bureau's consulting activities are a natural
result of the broad scope of its program and the special competence of many
of its staff in the physical sciences and engineering. Services of this kind

are rendered to other Federal agencies, to State and municipal governments,
and to various industrial groups.

Consulting services to the Federal Government ranged from the supplying
of specific technical information upon request to long-range projects that
were within the NBS mission but were sponsored by other agencies. Many
such projects were in the field of automatic data processing. For example,
a portable peer-rating machine, which rapidly computes group ratings of
individuals, was developed for the U.S. Army Personnel Research Office.
At the request of the Office of Technical Services, U.S. Department of Com-
merce, a system was designed for mechanizing the preparation of announce-
ment bulletins and indexes, inventory control, and storage and retrieval of
documents- In work done for the Patent Office, a remote inquiry station
was designed to permit easy and rapid communication between human oper-
ators at their respective locations and a central data processor, all of which
might be located within one building or might be separated by hundreds or
thousands of miles. Under the sponsorship of the Navy's Bureau of Supplies
and Accounts, assistance was given in the development of an efficient system
to procure and distribute the thousands of items required within the Naval
establishment and to control their purchase, storage, and distribution. An
information-handling system was designed for the Naval Intelligence Agency
to provide an efficient, low-cost means of storing, searching, and retrieving
intelligence data.

Consultative services were provided to the Weather Bureau on the trans-
mission and processing of photographic and infrared data generated by the
new weather satellites of the NIMBUS series. Systems analyses were con-
tinued to determine the feasibility of utilizing automatic data-processing
techniques in the activities and operations of the Interstate Commerce
Commission.

Assistance to State and municipal governments was principally in the field
of weights and measures. Although the Bureau itself does not have regula-
tory powers, it offers technical advice and consultation to local regulatory
bodies and it calibrates and adjusts State standards of weights and measures.
A major medium of cooperation is the National Conference on Weights and
Measures. Over 400 delegates from 39 states, Puerto Rico, and several
foreign countries attended the 48th annual meeting of this Conference, held
in Washington, D.C., June 10 to 14, 1963, under NBS sponsorship.

Important means of Bureau-industry cooperation were the Research Asso-
ciate Plan and the donor program. Under the Research Associate Plan,
technical, industrial, and commercial organizations can support work at the
Bureau that is of special interest to them, yet of sufficient general interest to
justify use of Government facilities. The work is done by research asso-
ciates who are paid by the sponsor but otherwise function as members of
the Bureau staff. At the present time the following groups are supporting
research associates at the Bureau:

Sponsor Field of Activity

American Dental Association Dental research

American Electroplaters' Society Galvanic effects associated with coating

failure
Properties of electrodeposited copper
American Society for Testing and Materials Cement and concrete reference laboratory

American Standards Association

Asphalt Roofing Industry Bureau

Bone Char Research Project, Inc.

Calcium Chloride Institute

NBS — Joint Committee on Chemical Analy-
sis by Powder Diffraction Methods:

ASTM, American Crystallographic Assoc,
Institute of Physics (British), National
Assoc, of Corrosion Engineers

National Academy of Sciences-National
Research Council

Porcelain Enamel Institute

Codes, specifications, and standards

Asphalt roofing research

Studies of adsorption and adsorbents

Hydration of portland cement

Standard X-ray diffraction powder patterns

Atomic physics
Porcelain enameled metals

The donor program was authorized in 1950 by Public Law 619 under
which the Bureau may accept funds for the purpose of furthering its work.
This arrangement permits individuals as well as technical, industrial, and
commercial organizations to support work at the Bureau when the results
are expected to be of value to the general public. During the past year, the
following projects were supported by gifts:

Donor
American Iron and Steel Institute

Brown and Sharpe Manufacturing Co.

Corrosion Research Council of the Engi-
neering Foundation

Edward Mallinckrodt, Jr.

Expanded Shale Clay and Slate Institute

International Business Machines

Link Aviation, Inc.

Pratt and Whitney

The Edward Orton Jr. Ceramic
Foundation

Field of Activity
Durability of steel pilings
Grant for standard samples program
Gage block program
Durability of steel pilings

Theoretical chemistry

Creep and shrinkage of concrete

Gage block program

Basic clay research

In the project sponsored by the American Iron and Steel Institute, the
Bureau investigated the extent of corrosion in steel piling that had been
driven into the ground. Data obtained from pilings which had been in
service in different geographic locations for 7 to 40 years showed that the
strength and useful life of the driven piling were not materially affected by
corrosion, apparently because of the deficiency of oxygen in "undisturbed"
natural soils. These findings are in sharp contrast to those of earlier cor-
rosion studies in which metal specimens such as pipe lines that had been
buried under "disturbed" soil conditions exhibited varying degrees of cor-
rosion. The disparate results are attributed to the differences in oxygen
content between the "undisturbed" piling environment and the "disturbed"
pipeline environment. Studies are now being made to determine the rea-
sons for this difference.

BACKGROUND RESEARCH

Study of the transitions that materials undergo at high pressures aids
in defining interatomic forces and the perturbing effects of neighboring
atoms on one another. During the year direct visual observations were
made of phase transitions and other changes occurring in a variety of
polymers subjected to extremely high pressures — up to one million pounds
per square inch. The polymers were compressed between diamond anvils
which served both as load-bearing surfaces and as light-transmitting media,
and a microscope was focused onto the specimen through the diamond. By
passing infrared and X-rays through the diamond pressure cell or by view-
ing the transformations through a microscope, it is possible to relate changes
in crystal structures to changes in bond energies, force constants, and vibra-
tion frequencies.

Large single crystals of metals, semiconductors, and other materials are
needed for many purposes in science and industry. However, single crystals
of most materials of practical interest are difficult to grow. The Bureau has
been making an effort to learn more about crystal-growing mechanisms
through study of simpler substances. It was found that at very low tem-
peratures large crystals of rare gases may be prepared and studied with
many of the same techniques that have been used at higher temperatures
on other substances. These gases are prototype molecular solids in which
the forces among the molecules are so weak that they crystallize at low tem-
peratures. Argon and krypton crystals were grown at temperatures near
the triple points of these elements, respectively 84 °K and 116 °K. Studies
of the properties and growth characteristics of these crystals were found
to be easily correlated with theory.

In cooperation with the George Washington University, a study was
made of the properties of coordination polymers formed by combining the
ligand 6/5 (8-hydroxy-5-quinolyl) methane with divalent manganese, cobalt,
nickel, copper, and zinc. Among the many potential applications for such
polymers is the fabrication of missile and rocket components. Results of
the study show that the decomposition temperatures of the polymers, and
hence their thermal stabilities, are directly related to the atomic numbers of
the coordinated metals. The findings has led to a better understanding of the
mechanism governing polymer decomposition and may be of particular use
in predicting the thermal behavior of coordinated systems when only a
minimum of experimental data is available.

Continuing research in statistical engineering dealt with applications of
probability theory to problems of the reliability of complex systems. A
mathematical study was made of the reliability of a system with spare parts,
where the spare parts can fail in storage as well as in use. An investigation
was begun of mathematical models for the description of changes through
time in the probability distributions of characteristics of electronic devices:
the dependence of these distributions on age and stress level was considered.

General areas of investigation in operations research included game theory,
graph theory, weapon system simulation, Boolean functions (important

in network circuit theory), and mathematical models of distribution net-
works. A number of mathematical topics relating to the "warehouse prob-
lem" (optimal location of a single processing facility) were identified and
explored.

Research in mathematical physics continued to be directed toward the
application of mathematical techniques to the solution of problems in physics
and engineering. Investigations in progress included the determination of
bounds on solutions of problems involving elliptic operators, especially those
of elasticity; the application of the "stroboscopic" method to the study
of nonlinear ordinary differential equations arising from vibration, acoustical,
and electrical circuit problems; the interaction of solar corpuscular radia-
tion and the earth's magnetic field; and studies of dynamic phenomena
which may affect the operation of plasma propulsion devices.

INTERNAL SUPPORT ACTIVITIES

Progress continued in the design and construction of the NBS linear
accelerator, Linac, now scheduled for installation at the Bureau's new
Gaithersburg (Md.) site in the spring of 1964. This accelerator will produce
one of the world's most intense electron beams with energies up to 100 million
electron volts, making it possible for the Bureau to enter new areas of nuclear
and atomic physics. Tests of the first prototype accelerator section were com-
pleted during the year, and a number of investigations were undertaken
which allow definition of the ultimate performance of the NBS linear ac-
celerator facility and of other comparable facilities.

A $5 million contract was awarded for construction of a high-flux research
reactor and associated laboratories at the Gaithersburg site. This reactor,
to be known as the NBSR, will enable the Bureau to fulfill its growing respon-
sibilities in the many rapidly expanding fields of atomic energy. It will
be used to advance the measurement, analysis, and understanding of radia-
tion effects on substances of all kinds.

INTERNATIONAL ACTIVITIES

On an international basis, the Bureau represents the interests of the Gov-
ernment and American science in matters dealing with the establishment and
maintenance of standards and the. establishment of values for scientific con-
stants. Most of this work is done through participation in a large number
of international groups such as the General Conference on Weights and
Measures, International Union of Pure and Applied Physics, International
Union of Pure and Applied Chemistry, International Scientific Radio Union,
International Commission on Illumination, and International Organization
for Standardization.

The Bureau, in cooperation with the Office of Technical Services, U.S.
Department of Commerce, has been actively participating, through the
American Standards Association, in the planning and development of pan-
American standards for commodities including textiles ; iron and steel ; cement

Members of the NBS Boulder Laboratories staff explain construction details of
the NBS microcalorimeter- — the U.S. standard of microwave power — to Dr.
Wolfdietrich H. Schaffeld {right), Head of the Microwave Physics Laboratory,
Physikalisch Technische Bundesanstalt, Braunschweig, Germany. (See
P. 19.)

and concrete; hides, leather, and tanning materials; and electrical equip-
ment. This program is basic to the economic development of the Latin Amer-
ican countries and to the expansion of trade among these countries and
between them and the United States. The Bureau has rendered assistance
in the field of weights and measures to several Latin American countries that
have requested it, and prototype standards suitable for use as the national
standards of developing countries are being procured for demonstration
and training purposes.

Another form of international cooperation is the reception of foreign
scientists as guest workers or visitors, and the training of foreign specialists
in the Bureau's laboratories. During the past year, 662 foreign scientists
from 45 countries came to the Bureau as visitors, and 138 trainees and guest
workers were received.

The Bureau continued a program initiated the previous year in which
funds are granted to scientific laboratories in certain foreign countries
in order to support research directly related to the Bureau's mission.
In the past two years, 29 grants and contracts totaling more than a million

dollars have been awarded to institutions in India, Israel, and Pakistan.
These awards are financed from excess balances of local-currency funds ac-
cruing to the United States from the sale of surplus farm products in past
years. Recent awards have been for work on imperfections in crystals, dy-
namics of crystal lattices, nature of the Moessbauer effect, analysis of poly-
mers, vapor pressure of refractories, and reflection of radio waves on
ionospheric layers.

In addition to the scientific results of these activities, the program has
resulted in an increased interest among foreign scientists in the kinds of
problems that are relevant to the Bureau's mission, in greater awareness
among Bureau staff members of the scientific potential in other countries, and
in intensified communication and exchange of visits.

In June 1963 a seven-man team of measurement specialists from this
country, headed by an Associate Director of the Bureau, visited the Soviet
Union for a month-long tour of various measurement laboratories. The
team consisted of six NBS staff members and one representative of industry.
Plans were made for a similar team of Soviet metrologists to visit the United
States later in the year. These visits are being conducted under the terms
of a United States-U.S.S.R. agreement for the interchange of information
and the exchange of visits by teams in 13 fields of technology. The U.S.
State Department, under whose general control the exchange program is
conducted in this country, requested that the Bureau arrange for the ex-
change of persons from the area of high-precision measurement standards.

ADMINISTRATIVE ACTIVITIES

During the past year the Bureau initiated a critical examination of its
management techniques for determining the needs and priorities of the users
of its services and for defining the objectives of its programs to assure the
most efficient application of NBS resources. Particular attention has been
given to the identification and emphasis of programs that support directly
the broad responsibilities of the Department of Commerce for promoting
economic growth through science and technology. New techniques are being
developed for the formulation, management, and evaluation of NBS pro-
grams in terms of certain broad program categories or "mission compo-
nents" which have been identified.

It has been recognized that the central program of the Bureau is concerned
with four related types of standards which are . of interest to two broad
customer groups. These are (1) basic measurement standards for the physi-
cal quantities and units, used by the scientific and engineering community,
(2) technological standards such as codes, methods of test, commodity stand-
ards, and engineering standards needed by the industrial community to
determine the quantity, quality, or performance of technological products
and materials of commerce, (3) standard reference data consisting of criti-
cally evaluated data on the physical and chemical properties of matter and
materials, and (4) standard reference materials for use in controlling in-
dustrial processes and maintaining the accuracy of measuring equipment.

The latter two categories of standards are needed by both customer groups.

In examining the total program of the Bureau, certain additional mission
components have been identified for management purposes. These include
the broad program of background research conducted by the Bureau to main-
tain contact with impending developments and to provide general scientific
competence, extensive consultative and advisory services provided for Gov-
ernment and private organization, and various technical services which sup-
ply internal support for NBS activities. In addition, the Bureau operates
research and technical service programs in certain "special mission" areas
for which the Bureau has a recognized central responsibility within Govern-
ment. The Bureau's Central Radio Propagation Laboratory, Data Process-
ing Systems Division, and Building Research Division conduct programs
of this type.

With the exception of these "special mission" organizations, NBS tech-
nical divisions are organized along the classical lines of science and engi-
neering, including divisions concerned with electricity, heat, mechanics,
analytical chemistry, atomic physics, etc. It has been necessary, therefore,
to devise new management techniques for examining the programs of these
subject matter divisions in terms of their contribution to the broader mission
components of the Bureau. It is believed that these management innova-
tions will enable the Bureau to be more responsive to the needs bf its cus-
tomers and to achieve better balance in the application of its resources.

To facilitate this new program management plan and to strengthen the
Bureau's activities which foster industrial technology, a new position of
Deputy Director for Technological Standards and Services was created.
This position will have responsibility for NBS programs which contribute
directly to the development of commercial and industrial standards and test
methods. Included are the commodity standards and international stand-
ards programs, which have been conducted by the Office of Technical Services
of the Department of Commerce since 1946, and were returned to the
Bureau near the end of the year. Assignment of these functions to the Bu-
reau concentrates in the Bureau all of the Department of Commerce programs
concerned with the development of industrial standards which provide the
common basis for exchange of technological products and services in in-
dustry and commerce.

The former Deputy Director has been redesignated Deputy Director for
Basic Standards and Services. He will be responsible for NBS programs
concerned with the development of basic measurement standards and sys-
tems, for the technical services associated with the dissemination of these
standards, and for the greatly expanded effort on standard reference data
which will result from the recent assignment to the Bureau of responsi-
bility for coordination of a National Standard Reference Data System (see
p. 8).

Funds obligated by the Bureau during fiscal year 1963 totaled $59,021,000.
including $9,627,000 for facilities. Of the $49,394,000 available for support
of the technical program, $28,492,000 came from direct appropriations to

The Engineering Mechanics Laboratory at the new NBS site in Gaithersburg
(Md.) is now being occupied by the first working groups to move to their new
quarters. (Seep. 21.)

the Bureau and $14,584,000 from other Government agencies and private
sources. In addition, calibrations, tests, and other reimbursable services
amounting to $6,318,000 were performed during the year. A more com-
plete presentation of financial data can be found in appendix 3.3.

The total staff of the Bureau at the end of the fiscal year was 4,160; 2,754
of these staff members were employed in the Bureau's Washington "Labora-
tories, and most of the remainder were attached to the NBS Boulder Lab-
oratories in Boulder, Colo. Additional information on staffing is available
in appendix 3.2.

Construction of Phase I of the Bureau's new laboratories near Gaithers-
burg, Md., was largely completed during the year and substantial progress
was made on the remainder of the facility. Phase I, which will be occupied
in the near future, includes a boiler plant that will supply heat and cooling
for all buildings on the site, and the engineering mechanics laboratory.
Erection of the large force-measuring machines that are an important feature
of the new mechanics laboratory is in progress, but will not be completed
for several months.

Construction of Phase II was started in July 1962 and is well under way.
This phase includes four buildings to house the administrative and service
activities of the Bureau and the radiation physics laboratory. The latter
building will contain the Bureau's new linear accelerator. Construction also
was started on the NBS research reactor near the end of the year (see
p. 19).

Phase III was started in October 1962 when a contract was awarded for
constructing the substructures of the seven general purpose laboratories.
This work was nearing completion at the end of the fiscal year and bids had
been requested for the remaining construction on these laboratories.

714-691 0—64-

Phase IV, which includes various special-purpose laboratories, is the last
element of the Gaithersburg facility currently planned and the only one
not now under construction. Planning for this phase continued during the
year. Also in the planning stage is a major new building to house the
rapidly expanding activities of the radio standards laboratory at Boulder,
Colo.

PUBLICATIONS AND TECHNICAL INFORMATION

To be fully useful, the information developed in the Bureau's work must
be communicated to the scientific and industrial community for application
in the laboratory and on the production line. Many channels are main-
tained to facilitate this flow of information.

Probably the main channel is the Bureau's publications program. NBS
publications are therefore suggestive of the scope and level of its technical
program. During the year these totaled 1,122 formally published papers
and documents. In addition, some 420 classified and unclassified reports
were issued to other Government agencies.

Among the major publications of the year was Dr. F. B. Silsbee's Systems
of Electrical Units (NBS Mono. 56) . It surveys the various systems of units
used in electricity and magnetism and briefly traces their historical de-
velopment. Dr. Silsbee, one of the world's leading authorities in the field,
compares the views of the theoretician and the experimentalist in the deri-
vation of the units.

In his discussion, Dr. Silsbee points out that preferences and philosophies
regarding systems of units have changed substantially over the years and
are still under discussion by international standardizing bodies. This
Monograph is intended as a stimulus to further development, understanding,
and utilization of systems of electrical units.

Another major publication was Tensile and Impact Properties of Selected
Materials from 20 to 300 °K (NBS Mono. 63) . The materials referred to are
structural materials for use in low-temperature applications — alloys of
aluminum, cobalt, copper, iron, nickel, and titanium, and two metal-bonded
carbides. Included are tensile strength, yield strength, elongation, and
reduction of area values; stress-strain curves; and impact data.

Standard X-ray Diffraction Powder Patterns (NBS Mono. 25, Section 2),
the twelfth in a series with this title, also appeared this year. This volume
contains 37 standard patterns to aid chemists in identifying unknown crys-
talline materials by X-ray diffraction. Radiobiological Dosimetry: Recom-
mendations of the International Commission on Radiological Units and
Measurement (NBS Handb. 88) is in effect a handbook for the radiobiol-
ogist and considers methods for improving accuracy and comparability of
absorbed dose measurements.

Of the 1,122 formal publications issued during the year, 180 were published
in the Journal of Research, and 736 in the journals of professional and
scientific societies. Also, 132 summary articles were presented in the Bu-
reau's monthly Technical News Bulletin. In the nonperiodical series of

publications, 74 papers were published: 18 in the Monograph series; 4 in
the Handbook series; 3 in the Miscellaneous Publication series; and 49 in
the Technical Note series.

Central Radio Propagation Laboratory Ionospheric Predictions, the Bu-
reau's third periodical, which is published for a one-month period three
months in advance, presented radio propagation data needed for determining
the best radiofrequencies to use in long-range radio communications. A
fundamental change in form and content was made in the Predictions be-
ginning with the January 1963 issue. The predictions are now prepared
by a method of numerical mapping using a high-speed electronic computer.
The new format includes tables of coefficients which, when used as input
data with a suitable program, make possible the use of a computer
for calculation of detailed high-frequency radio propagation predictions for
any application. World prediction maps for every even hour, Universal
Time, are provided for subscribers without access to computer.

A list of publications for the fiscal year, which includes several papers
published in the previous year but not reported, is given in the appendix,
section 3.7 (p. 212) .

Secretary of Commerce Luther H. Hodges (right foreground), Assistant Secre-
tary of Commerce for Science and Technology J. Herbert Hollomon (speak-
ing), and NBS Director A. V. Astin (center) at a preview of the NBS Open
House commemorating the Commerce Department's 60th Anniversary. The
special preview was held for Government officials, Congressional staff, and
members of the press. (See p. 24.)

Scatter Radar: Space Research from the Ground, a 23-minute, 16mm color
movie, was released during the year. The picture tells the story of the
Jicamarca Observatory, new NBS facility near Lima, Peru. Jicamarca,
largest installation of its kind in the world, utilizes a 22-acre radar antenna.
It probes the upper atmosphere to measure electron densities, has already
made observations of the planet Venus, and will study the solar corona and
solar gases.

On May 11, 1963, the NBS Washington laboratories were opened to the
public for the first time in many years. The open house program was a part
of the celebration of the 60th anniversary of the Department of Commerce.
Approximately 7,000 persons visited during the day and went on selected
tours among the more than 100 laboratories and special exhibits that were
open for public inspection. At the NBS Boulder, Colo., laboratories, the
anniversary was also commemorated by special tours and open houses for
high-school students and the general public.

During the year, the Bureau participated in 18 scientific and technological
exhibitions, with exhibits depicting the Bureau's research programs. Fea-
tured in several of these exhibits was a working model of the NBS ultrasonic
thermometer, operating at liquid helium temperatures. Typical of the year's
shows were National Academy of Sciences, Washington, D.C. ; International
Symposium on Humidity and Moisture, Washington, D.C. ; Northeast Com-
merce and Industry Exposition, Boston, Mass.; National Electronics Con-
ference, Chicago, 111.; and National Scale Men's Technical Conference and
Exhibit, Cleveland, Ohio.

The Bureau's motion picture program included 3,694 showings of NBS
films to a total audience of 434,359, including educational television.

2. HIGHLIGHTS OF THE
RESEARCH PROGRAM

The Bureau's technical program is carried out through organizational units
called divisions. These are shown in appendix 3.1 in numerical order. A
review of selected research and development programs is presented in this
section under headings corresponding generally to these organization units
but rearranged to bring together related types of activity.

2.1. PHYSICS, ELECTRONICS, AND
MEASUREMENT STANDARDS

2.1.1. METROLOGY

The metrology laboratories of the Bureau provide a central basis for a
system of physical measurement by maintaining, developing, and disseminat-
ing standards for commonly used physical quantities such as length, mass,

volume, density, and angle, as well as for light, color, electromagnetic radia-
tion, and other optical and photographic quantities.

With the assistance of the Advanced Research Projects Agency, work on
the thermal and optical properties of materials was expanded during the year
to include measurements of the optical properties of infrared-transmitting
materials. Research is in progress on the measurement of the transmissivity,
reflectivity, emissivity, homogeneity, and scattering properties of materials
widely used in space, industrial, and research applications.

The calibration program has been strengthened by the use of automatic
measuring and computing equipment, particularly in the calibration of mass
standards. The resulting savings in human labor formerly required per-
mitted the Bureau to offer new calibration services with less delay and to
devote more effort to the development of improved measuring systems and
standards.

A New Standard of Spectral Irradiance. The accurate measurement
of spectral irradiance has assumed increasing importance in connection with
studies of the irradiance to which space vehicles will be subjected. The
making of such measurements was facilitated by the development of a new
standard of spectral irradiance, a 200-watt quartz-iodine lamp with a coiled-
coil tungsten filament operating at about 3000 °K. The lamp is obtained
from a commercial source and is calibrated in microwatts per square centi-
meter of receiver per nanometer of waveband pass over the spectral range
of 0.25 to 2.6 microns (ji) . Unlike the standards of electrical radiance
which have been available for several years, the lamp is used without aux-
iliary optics and, because of its small physical size and high operating
temperature, it provides relatively high spectral irradiances.

Basis for Color Measurement Amended. Since 1931 the interna-
tional basis for color measurement has been the color-matching functions
for the average normal eye as derived statistically from measurements made
by a large number of observers. These functions were obtained from ob-
servations made of visual fields subtending 2 degrees at the eye and they give
satisfactory predictions for field sizes between 1 and 4 degrees. However,
industrial inspections of many products such as paints, papers, plastics,
ceramics, and textiles are customarily made by checking a large specimen
(that is, a visual field subtending 10 degrees or more) against an equally
large color standard, because smaller color differences are detectable this
way. But the color matches thus set up often fail to hold for the same sam-
ples viewed at a distance. This apparent discrepancy results from the fact
that the central part of the normal eye is covered by a spot of yellowish
pigment.

In 1957 the International Commission on Illumination requested the Bu-
reau to derive a set of color-matching functions for the 10-degree field from
observations of such fields made by a number of observers at the National
Physical Laboratory in Teddington, England, and at the State Optical Insti-
tute in Leningrad, Russia. The derivation was completed in 1959 and the
resulting functions were subjected to intensive practical trials in Canada,

Great Britain, Russia, and Spain, as well as in this country. At the 1963
meeting of the Committee of Experts on Colorimetry of the International
Commission on Illumination in Vienna, Austria, these functions were rec-
ommended for use in color measurement as a supplement to the 1931
functions.

Calibration of Flashtubes. The use of flashtubes (strobelights) is
becoming increasingly important for both terrestrial and extraterrestrial sig-
nalling purposes; hence, evaluation of the flux produced by a flashtube in
terms of its effect on the human eye is required. Accordingly, the Bureau
recently undertook the calibration of flashtubes, reporting either the candle-
seconds per flash in a specified direction or the lumen-seconds per flash, as
required. Both the flashtube and its associated power supply are submitted
for calibration, together with a triggering mechanism which triggers the
flashtube repetitively at a stable rate of about one or two flashes per second.

Fluorescent Lamp Measurements Intercompared. The Bureau
recently participated in the first international intercomparison of photometric
and colorimetric measurements on fluorescent lamps with the national lab-
oratories of seven other countries. Three 40-watt fluorescent lamps of each
of three different colors were supplied by the British National Physical Lab-
oratory to the participating laboratories. Laboratory measurements made
of total light output (luminous flux) covered a spread of about 4 percent,
with the individual results varying from —2.4 to +1.5 percent from the
world mean. The NBS value was — 0.8 percent from the mean. Although
the variance in the results was not deemed exorbitant, the International Com-
mission on Illumination requested the International Bureau of Weights and
Measures to take steps to narrow the spread.

Color measurement results were more divergent and seemed to depend
on whether visual matching or spectroradiometry was used. The Bureau
values obtained by means of a colorimeter (calibrated with fluorescent lamps
that had been calibrated visually by incandescent lamps and colored filters)
were in good agreement with the world mean. However, Bureau chromaticity
results derived from spectroradiometric data were in poorer agreement.
Spectroradiometric results obtained by U.S. lamp manufacturers were com-
pared and were also found to contain substantial differences. Consequently,
since the international goal is to place the colorimetry of fluorescent lamps
on an objective basis that is dependent upon spectroradiometric data,
an investigation of the whole problem of data reproducibility is being
undertaken.

Equipment Developed for Calibrating Thermal Detectors. A
new standard "blackbody" detector and a filter spectroradiometer for use
in the calibration of thermal detectors were developed. The detector con-
sists of an inside-blackened gold-foil conical receiver to which is attached
a series of thermocouples. It has a spectral emissivity of 0.99 or more
throughout the spectrum from the short ultraviolet to the long infrared. The
filter spectroradiometer consists of narrow-band interference and other
glass filters, and mercury line sources, tungsten lamps, and globar radiators.

During a calibration, the sources with the filters produce spectrally homoge-
neous lines and narrow bands at some twenty wavelengths between 0.25 and
20 /x to successively irradiate uniformly over their entire surfaces the new
standard detector and the detector under test. The relative spectral response
of the test detector is thus measured as the ratio of the two responses as a func-
tion of wavelength. All commercial thermal detectors measured so far
vary in response with wavelength by 5 percent or more. However, their cali-
bration permits their use in precise radiometric investigations.

Equipment Developed for Densitometric Calibrations. A quan-
titative method of photometric attenuation was developed for densitometric
calibrations. A rectangular aperture fitted with a sliding straight-edged
shutter is employed. Light flux through the aperture is made proportional
to the open aperture area by a compensating procedure, as follows: When a
thin slit is moved across the aperture, the light passing through the slit to
a detector is compared to the light coming from the same source by a differ-
ent path. If the response of the detector is constant as the slit moves, the
shutter is replaced, and the flux through the aperture to the detector is then
known to be proportional to shutter displacement, which can be measured
precisely. If detector response is not constant, the aperture edges may be
shaped or an optical compensator may be placed in the aperture to produce

Measuring the refractive indices of synthetic calcium fluoride. Such values
provide a basis for selecting optimum crystalline materials for the design of
optical components and systems. (See p. 30.)

the required condition. Two slits may be used to establish an exponential
or inverse square relationship to the shutter displacement if desired. The
method requires about one-tenth the space required by the inverse-square
method now in use, and it is less subject to certain errors. Its applicability to
the calibration of photographic-density step tablets was confirmed experi-
mentally and the equipment is being refined.

Refractive Index of Calcium Fluoride. The increasing use of cal-
cium fluoride for infrared and ultraviolet optical devices, particularly in
military detection and guidance systems, suggested the use of synthetic
calcium fluoride — which has been available for several years — for such
applications. However, the refractive index of the synthetic material, which
must be carefully considered in the design of such devices, was known for
only the visible region of the spectrum. The Bureau therefore measured the
refractive index of both a synthetic and a natural crystal of calcium fluoride
over a wavelength range from 0.23 fi in the ultraviolet to 9.7 /x in the infrared.
Results indicate that synthetic crystals, when properly prepared, are com-
parable in refractive properties to natural crystals.

Generalized Lens-Bending Procedure Developed. A tool often
used by the optical designer is the well-known procedure of bending a lens
element; that is, varying the curvatures of both of its refracting surfaces by
some common increment. The increment is an independent variable, while
the two curvatures of the lens system represent parameters dependent on it
for their modified values. A family of lens elements is thus defined, each
member of which possesses useful properties in common with the original
lens element. When this element is a thin lens for which the refractive
indices are the same on both sides, the paths of the marginal and prinr.inal
paraxial rays are left invariant over the remainder of the lens system.

A generalized lens-bending procedure recently developed for the case
of thick lenses and unrestricted refractive indices possesses this same invari-
ance property with respect to the path of the two paraxial rays. The pro-
cedure required variation (by unequal amounts) of the curvatures of the usual
two surfaces, together with related variations of two vertex separations. In-
dices of refraction are not modified. Thus, variation of four lens parameters
is obtained as a function of the independent variable which specifies the
amount of "bending" desired. The chief advantage of generalized bending
is that it allows variation of third-order aberrations arising from a single
element of a lens system, independently of the remainder of the system.

Technique for Deriving Principal Curvatures of Wave Fronts.
A mathematical technique was recently developed for determining the prin-
cipal curvatures of a refracted or reflected wave front in an optical system.
The technique extends geometrical analysis beyond traditional ray tracing
for a large class of optical systems. Since the amplitude of the electro-
magnetic wave associated with the wave front is inversely proportional to its
Gaussian curvature, the technique is useful in any attempt to describe quan-
titatively the physics of light propagation in lenses.

Images, photographed at various focal planes on the lens axis, formed by placing
a perforated plate on the front surface of a long focal length lens and illumi-
nating it with collimated light. These "spot diagrams" aid in the determination
of the geometrical properties of the lens. (A) taken on the lens side of the
position of best focus; (B) taken at the position of best focus; (C) taken be-
yond the position of best focus. (See p. 30.)

An immediate application was found for the results of this work in a
study of designs for grating spectrometers. Long-range applications are
anticipated in the area of physical optics. A computer program was pre-
pared to obtain automatically processed data for required calculations.

Image Evaluation. In an image evaluation program on photographic
objectives, work is in progress on the effects of known defects (such as
striae, bubbles, feathers, streaks, and surface scratches) in objective lenses
on limit of resolution, wave front shape, frequency response, and general
picture quality. Five lens samples are being observed, supposedly differing
only in the glass from which they were made. A lens of good glass quality
is included in the group as a control.

Measurement of Wave Fronts. A method was developed which per-
mits the measurement of the departure of the wave front emergent
from a lens from a true spherical wave front in terms of wavelength. The
method involves the measurement of the displacements of the central fringe
of an interference pattern. The pattern is produced by the introduction of
a double slit into the beam of light incident upon the lens. Measurable dis-
placements of the pattern occur as the double slit moves across the front
of the lens. An accuracy of ±0.02 wavelenth is attained.

Stored Microfilms Inspected. As part of a study of the permanence
of photographic materials, large numbers of microfilms of Government
records were inspected. The inspections revealed a rather widespread in-
cidence of microscopic defects after 2 to 20 years of storage. These defects,
confined almost exclusively to negative microfilm, are circular reddish spots
from 15 to 150 fi in diameter, some having a concentric ring structure, or a
decrease in density and general broadening of printed lines and other
information. Practically no information loss was observed, but the necessity
of periodic inspections was made clear.

Microcopy Chart Designed. In response to demands of science and
industry, a microcopy resolution test chart was designed. When proposed
minor amendments are made in existing microcopying specifications, the
new chart will replace the current NBS Standard Sample No. 1010. Chart

color, line type, contrast, line-to-space ratio, number of lines per group,
and length-to -width ratio of lines conform to current specifications. Very
small changes were made in a few spatial frequencies to make the series
conform to an international standard preferred-number series. A slight
alteration in the layout of the patterns permits the frequency range to be
extended to higher or lower frequencies and permits the chart to be abridged
conveniently when desired. A small change in the size of the sheet will have
no effect upon the usefulness of the chart but will accomplish considerable
economies in time and materials in chart production.

Method Developed for Measuring Thiosulfate in Processed Film,
A new analytical procedure for measuring the thiosulfate radical remaining
in photographic film after processing was developed. Such measurements
are routinely done at the Bureau to ascertain conformance to microfilming
specifications which require that films be sufficiently well washed to reduce
thiosulfate concentration to less than 0.005 mg per square inch (reported
as sodium thiosulfate) . The current standard analytical method has been
in use for the past 30 years. The new procedure, which is based on the
same chemical principles, reveals two to three times as much residual thio-
sulfate as does the current standard procedure. A new method of meas-
uring the residual non-image silver in processed film was also developed.

Length Measurement Research. Ultra-precise methods for making
length measurements are being sought so that length standards may be
calibrated to an accuracy approaching a tenth of a microinch. Toward
this end, an ellipsometer was acquired to determine the thickness of the
thin film existing between joined gage blocks. In application, these films
are an inherent part of the length of end standards of length. To aid in
this research, a theory was developed on the behavior of light beyond a
surface normally thought to be totally reflective.

Thermal Expansion Measurement Capability Extended. Addi-
tional data are needed on the thermal expansion of materials in the extreme
environmental conditions of outer space and in the thrust nozzles and heat
shields of space vehicles. So equipment designed to increase Bureau meas-
urement capability from 1000 to 1700 °C was installed and operated thus
far at temperatures above 1600 °C. Cryogenic equipment was also de-
signed and is now under construction. This equipment will extend the
Bureau's minimum temperature range capability to —250 °C.

Wave-Front-Shearing Interferometer. A wave-front-shearing inter-
ferometer was developed and applied to the testing of mirrors and lenses.
In one study, it was placed at the focus of a 26-in. refractor at the Uni-
versity of Virginia, in probably the first interferometer test of an astro-
nomical telescopic in situ. Four photographs of interference fringes were
obtained by changing the direction of shear 90° between each photographic
operation. The shape of the wave front as it emerged from the objective
could then be computed. By way of further development, a means was
devised for rotating the fringes into the direction which would provide the
best accuracy.

Screw Thread Standardization. Thorough consideration was given
by the American Standards, Association's Sectional Committee Bl, the Inter-
departmental Screw Thread Committee, and a recent American-British-
Canadian Conference on Engineering Standards to the revision of the defini-
tions of pitch, groove, ridge, and functional diameters of screw threads.
The revisions were correlated with types of limit gages and measuring meth-
ods to clarify a dimensional control problem. The new concepts developed
will be published in revisions of Nomenclature, Definitions, and Letter
Symbols (Section II of NBS Handbook H28) , and American Standard
B1.7.

In other studies, a critical review was made of the factors which affect
the accuracy of pitch (or groove) diameter measurements by the use of
thread wires, and proposed revisions in standard measuring practice were
developed. The revisions will provide optimum compensation of elastic
deformations under measuring forces and will prevent excessive compressive
stresses which would cause permanent deformations.

Laser Produces Fringes Over 200-Meter Path. Improvements in
the design of a helium-neon laser permitted its output to be operated at a
single mode (the highly monochromatic portion of a single spectrum line) .
It was found that a quartz spacer tube maintained constant spacing of the
instrument's end reflecting plates and thus the stability of laser frequency.
In recent work with the laser, its infrared light of wavelength 11,530 A
applied to a modified Michelson-type interferometer produced fringes that
were first converted to visible wavelengths and then observed and photo-
graphed over a 200-meter optical path.

Cockpit Lighting in TFX Aircraft. Advisory services, provided by
the Bureau to Navy, Air Force, and General Dynamics Corporation engineer-
ing personnel, led to standardization of the color of illumination for the cock-
pit lighting of TFX (F-lll) aircraft, and to the first specified use of electro-
luminescent sources for cockpit lighting in an American plane. The stand-
ardization will result in monetary savings in the production of this plane.

Accuracy of Spectral Transmittance Standards Investigated. For
a number of years the Bureau has been issuing glass filters (selenium red,
carbon yellow, copper green, and cobalt blue) for use as spectral transmittance
standards in checking the photometric scale of spectrophotometers throughout
the visible spectrum. The NBS reference standards used to calibrate these
filters are periodically evaluated at the Bureau to determine their true spectral
transmittance values. However, the results of two recent recalibrations of
a set of the issued filters suggested a possible drift in the spectral transmittance
values of the NBS standards. An extensive recalibration was therefore
undertaken of the latter. The measurements obtained showed that the values
of spectral transmittance at some wavelengths differed slightly from previously
assigned values but not by amounts exceeding the combined uncertainties of
former calibrations and the present recalibration.

Measurement of reflective properties of materials used for balloon satellites.
The measurements will provide a basis for analysis of the effect of radiation
pressure on such satellites. (See p. 34.)

Gonio photometry. To assist the National Aeronautics and Space Ad-
ministration with an analysis of the effect of radiation pressure on a balloon
satellite, goniophotometric measurements were made on plane specimens of
the skin at a large number of angles of incidence and viewing. The results
were reported in terms of the intensity factor, that is, the ratio of radiant
intensity to incident flux. The data were obtained with a manual point-by-
point goniophotometer. Subsequently, the Bureau received delivery of a
custom-built recording monoplane goniophotometer. The new instrument
will greatly facilitate goniophotometric investigations of reflected and trans-
mitted flux distributions from all kinds of materials.

2.1.2. MECHANICS

The Bureau's work in mechanics is primarily concerned with the develop-
ment and improvement of measurement methods for mechanical phenomena
in solids, liquids, and gases; the establishment of required standards in
mechanics and the relation of such standards to prototype standards; the
support of these activities by theoretical and experimental research on
mechanical phenomena ; the determination of physical constants of particular
importance in mechanics; and provision of assistance to other laboratories
in relating their measurements to a common basis (or to established stand-
ards) by transfer standards, calibration services, and other means. Measure-
ment areas include sound pressure and intensity, shock, vibration, force,
strain, pressure, vacuum, viscosity, and rate of gas and liquid flow.

These measurement areas are of importance to scientific and engineering
programs (including those of the space effort) which require great accuracies
over wide ranges under extreme temperature environments. Special empha-
sis is therefore given to research directed toward meeting these needs.

The design of special-purpose equipment to be installed in the Engineering
Mechanics Laboratory at Gaithersburg, Md., was completed. This equip-
ment includes deadweight testing machines of 113,000-lb, 300,000-lb, and
1,000,000-lb capacity and a universal testing machine of 12,000,000-lb ca-
pacity. Design work progressed on two other laboratories, one for sound
experiments and the other for fluid mechanics research. When these three
facilities are in operation, it will be possible to provide improved services in
several of the measurement areas in mechanics.

Vibration Amplitudes Measured, The range of amplitudes over
which vibration-measuring instruments can be calibrated photometrically
with a Fizeau optical interferometer was extended by the development of a
method to replace the human observer method previously used. The new
method covers amplitudes from 1090 angstroms (A) up to about 1 micron
(about 4 to 40 microinches) and the entire range of audiofrequencies up to
20,000 cycles per second (c/s), in contrast to the amplitude range of the
old method of from 72 to 4400 A.

A unique feature of the new method is the vibration of both plates of the
interferometer, one at a modulating frequency much lower than the calibrat-
ing frequency of the other. The resulting modulated light flux is detected
by a photomultiplier. The photomultiplier signal is analyzed electronically
so that a meter shows a sharp null when the amplitude of vibration of the
plate, moving with the vibration pickup attached to it, reaches one of a
number of accurately known values determined by the optical wavelength.
This method improves the precision of Bureau calibrations and reduces the
time required to perform them.

Microphone Calibration. Pressure calibrations of condenser micro-
phones are usually carried out in small hydrogen-filled couplers at ambient
barometric pressure. During the past year, an apparatus was developed
which prevents excessive loss of hydrogen from the coupler for long periods
of time. This apparatus connects the coupler's capillary tubes to relatively
large containers of hydrogen and vents the containers to the atmosphere
through additional capillary tubes. The system provides ample time for
performing reciprocity calibrations accurately in the three cubic centimeter
couplers that are used over a frequency range from 500 to 20,000 c/s.

Portable Tube Designed for Sound- Ab sorption Measurements.
A portable acoustical impedance tube was developed as an instrument for
practical research on sound-absorbent materials. The tube makes precision
measurements of impedance and sound absorption in both laboratory and
field installations, over the frequency range from 400 to 900 c/s. It is useful
for the development, manufacturing control, and acceptance testing of acous-
tical materials installed in various buildings, as well as for the determination
of aging, staining, and redecoration effects on sound absorption.

Cavitation Data Obtained. Cavitation, or the opening up of cavities
in liquids subjected to tension, has been intensively studied for years.
Hydraulic cavitation, such as that occurring on and about ship propellers,
is of great practical importance since it wastes power and damages propeller
blades. Another type is sonic cavitation, in which tension occurs during
the rarefaction phase of an intense sound wave. This effect is commercially
important in sonic processing.

A fundamental problem in sonic cavitation is the origin of the nuclei, which
are very small air-filled or vapor-filled cavities. Theory indicates that they
must preexist in order for catastrophic expansion to take place at the levels
of tension (cavitation threshold) observed. Workers abroad report evidence
that nucleation is primarily induced by secondary neutrons connected with
cosmic radiation. Independent experiments along these lines are under way
at the Bureau, jointly sponsored by the Office of Naval Research.

Cavitation thresholds are notoriously irregular, and quantities of data are
needed on these thresholds for statistical processing; however, an inordinate
amount of labor is involved. So in the current Bureau study, a device which
automatically measures and records the cavitation threshold of a sample of
water 100 times a day was developed. After automatic processing of these
data by an electronic computer, it may be possible to separate the effects of
the numerous variables involved and thus obtain additional evidence on the
nucleation process.

Measurement of Impact Sound Transmission in Buildings. A
comprehensive study was undertaken during the year to develop a standard
test method for the measurement of impact sound transmission. In this study,
in which three other laboratories participated, a roundrobin series of impact
tests with a standard tapping machine was conducted on basic 4-in. -thick
concrete floor specimens. The specimens were subsequently surfaced with
acoustical materials and again tested. Field measurements on floor struc-
tures nominally identical to those measured in the interlaboratory program
are currently in progress to determine the correlation that exists between
laboratory and field measurements.

This study, jointly sponsored by the Army, Navy, and Air Force, was
closely coordinated with work of the Federal Housing Administration, which
recently developed the first impact-noise criteria for use in this country. The
criteria, based in part on NBS laboratory measurements, were recently pub-
lished as FHA Report No. 750, "Impact Noise Control in Multi-Family
Dwellings." This document is a clear and concise guide for the control of
impact noise, and it is designed for use by the FHA insurance staff as well
as by architects and builders.

Infrasonic Waves Studied in the Atmosphere and in the Earth.
Preliminary comparisons of sound waves received at the Bureau's new in-
frasonics station in Boulder, Colo., and at the station in Washington, D.C.,
reveal a number of time intervals in which signals were recorded from the
same source in a distant geographical area. Comparisons of arrival direc-
tions at the two stations now being made will allow some fairly precise deter-

Measurement of impact noise produced on floors by footfalls. The sound is
transmitted through the floor and measured in the room below. Results pro-
duced in this way are being compared with measurements of noise from the
standard tapping machine usually used in laboratory work. Sound measure-
ment is an important step in the formulation of sound insulation requirements
in building codes. (See p. 36.)

minations of the geographical areas from which signals are generated by
ionospheric disturbances, tornadic storms, volcanoes, and by presently
unknown sources.

Observations with a temporary infrasonics station at Fort Yukon, Alaska,
confirmed that infrasonic waves, previously associated with geomagnetic
activity from measurements at the Washington, D.C., station, were caused
by auroral disturbances. Comparison with geomagnetic fluctuations and
cosmic radio noise absorption effects indicated an atmospheric pressure wave
source intimately connected with the behavior of the auroral ionosphere.
The temporal and geographical distribution of the ionospheric disturbances
are controlled by the position of the sun and the level of solar activity.

Further observations on infrasonic waves (having periods of about 6
seconds), commonly called microbaroms, confirm the hypothesis of their
oceanic source. The ocean waves periodically arriving on the eastern sea-
board can radiate enough sound to cause microbaroms to be observed at
Washington. They are present also at Boulder, but substantially weaker
because of the greater distance from the coasts of North America.

Infrasonic waves radiated by tornadoes in the midwest continue to be
received at the Washington station. They are also observed at the Boulder
station and at the Boston station of the Air Force Cambridge Research Labora-
tories. Such waves have periods longer than 10 seconds. (Other aspects
of this study are discussed in 2.3.4, Geomagnetic Micropulsations and Infra-
sonic Pressure Waves, page 146.)

Three seismometers of a type developed at the Bureau were installed at sites
several kilometers apart in the Washington area. A telemetry system has
been worked out so that seismic vibrations are simultaneously recorded at the
Bureau. The seismometer system is now being used to determine the speed
and direction of microseisms, having periods near 6 seconds, propagated
through the Washington area. The possibility of a common origin for both
microbaroms and microseisms is being investigated.

Audiometry Research, People usually hear by sound waves which
travel down the ear canal to the eardrum (air conduction), but sounds can
also be heard when a vibrator is applied to the bones of the head (bone con-
duction). The least sound that can be heard is called the threshold, and a
knowledge of its level is important in the medical diagnosis of impaired hear-
ing. Also of importance are the relative levels of the air-conduction and bone-
conduction thresholds.

Air-conduction thresholds measured on 12 young otologically normal
persons were used to determine the maximal displacement amplitudes of the
basilar membrane in the inner ear. Bone-conduction thresholds in terms
of vibratory displacement of the skull, measured on the same group, were
related to the displacements of the basilar membrane. These data were then
used to determine vibratory motion transmission characteristics for the
mastoid and forehead bones. Data obtained on the mechanical impedances
of the head bones for the same persons were combined with the threshold
displacements to obtain basic information on the vibratory power required
for hearing by bone conduction.

Data on the threshold of hearing by air conduction are best stored as sound
pressures produced at various frequencies by an earphone placed on a
coupler. The coupler contains a small volume of air and a microphone for
measurement of the sound. Such a coupler was developed years ago at the
Bureau as a standard for audiometric measurement. The technical com-
mittee on electroacoustics of the International Electrotechnical Commission
recently decided that this coupler was suitable for storage of threshold data
newly adoped by the International Standards Organization. The committee
will therefore issue a report describing the coupler to facilitate international
use of standard thresholds in audiometry.

Improvements Sought in Pressure and Vacuum Measurements.
The range of pressures (from 10~15 millimeters of mercury to 50,000.000 psi)
of interest in science and industry is so vast that many different types of in-
struments and techniques are required. Efforts are being made at the Bureau
to extend pressure-measurement capability by improvements in the design
and construction of apparatus, and to develop better experimental techniques.

In the range of high-pressure measurement, the freezing pressure of mer-
cury at 0 °C was determined to be 109,722 psi with an accuracy of ±30 psi.
This pressure fixed point is adequate as a calibration point to serve current
needs. The mercury experiment verified the advantage of a manganin re-
sistance pressure gage as a working pressure gage. The full potential of
manganin gages has not been realized, so the electrical system for pressure

measurements is being improved in order that more detailed study may be
made of the pressure-temperature-resistance characteristics of manganin.

A new piston gage is under construction for use in a more accurate de-
termination of the phase transition of bismuth between 365,000 and 370,000
psi. This transition has served as the principal calibration point for the
ultra-high-pressure range. Work has continued on the "two-stage" modi-
fication of a tetrahedral apparatus in which stishovite, a form of quartz, has
been produced at a pressure of 2,000,000 psi and a temperature above
3000 °F.

Studies in vacuum measurement were continued in the search for force-per-
unit-area techniques as contrasted to the indirect methods usually employed
in the field. Such techniques are needed to increase the accuracy of conven-
tional vacuum measurements. A detailed study of capillarity effects on the
widely used McLeod gage is being carried out. Volume expansion of a fixed
quantity of gas was used to study McLeod and ion gage characteristics.
Preliminary experiments on an interferometer — oil-manometer led to the
design of an improved model which is now nearing completion.

Computer Techniques Applied in Turbulence Studies. In col-
laboration with the David Taylor Model Basin, a digital computer technique
is being applied to the measurement of the statistical properties of turbulence.
Thus far, probability distribution, time, space, and space-time correlations
in an isotropic turbulence field have been measured. The results demonstrate
the feasibility of applying such methods to the measurement of turbulence
and provide extensive information as to the space-time transformation and
higher order correlations.

Correlation measurements up to the eighth order were obtained by the
computer technique, representing a significant step beyond the fourth-order
correlations previously derived by conventional analog methods. The com-
puter application to the measurement of other pertinent quantities such as
derivatives, higher orders thereof, and joint probability distributions will
be investigated.

Boundary Layer Instability and Effect of Roughness. Due to the
instability of fluid laminar flow in a thin layer near a wall, known as the
boundary layer, ensuing turbulent motions completely alter the characteristics
of the flow. It is known that instability gives rise to selective amplification
of initially small disturbances and that the end result of the process is a
breakdown of the flow to the turbulent state. In a program sponsored by the
National Aeronautics and Space Administration, the manner in which turbu-
lent motions begin as the result of an instability has been under investigation
for some time.

In the investigation, the breakdown process was traced by means of sensi-
tive hot-wire probes through its various stages. This technique revealed that
before the motions become turbulent and while they are still wavelike in
character they become three-dimensional. In doing so, they modify the flow
at certain localities along the wave train and give rise to a second type of
instability — the so-called inflectional instability — from which final breakdown
ensues.

714-691 0—64-

When a wall is not smooth, the roughness elements usually cause or promote
transition to turbulent flow. While empirical rules for this effect have been
established, the mechanism involved has in general remained obscure. The
present study has, however, revealed the mechanism involved when the rough-
ness is a single, two-dimensional element commonly called a trip wire.
Systematic measurements showed that this type of roughness element promotes
transition by destabilizing a region of modified flow downstream from the
element. In this more unstable flow field, selective amplification of ambient
disturbances is increased. The observed amplifications are in line with
existing stability theory.

Standards Designed for Million-Pound Forces, As a part of a
program to support the Nation's efforts in space, the Bureau is constructing
a series of deadweight force machines in ranges up to one million pounds at
its new laboratories now being built near Gaithersburg, Md. The continued
accuracy of these machines is being assured by the acquisition of a set of
three reference standards of mass made of stainless steel in units of 10,000,
20,000, and 30,000 pounds. These weights, the largest ever constructed to
meet Bureau requirements, have been adjusted to an accuracy of one-thou-

Ten-, twenty-, and thirty-thousand pound mass standards compared to a one-
kilogram mass. These weights, the largest ever constructed to meet NBS Class
C requirements, will be used in the deadweight force machines now under con-
struction at the new Gaithersburg laboratories. (See p. 40.)

sandth of one percent. A precision scale, having a capacity of 30 tons and
sensitive to a variation of 2 ounces, will permit comparison of the working
weights of the deadweight machines against the reference standards.

Compact Precision Centrifuge Constructed. A centrifuge with a
36-in.-diameter table was designed and constructed to calibrate precision
accelerometers over an acceleration range from 1 to 80 g with errors that
do not exceed 0.1 percent. For calibration of servoaccelerometers, accurate
knowledge of the location of the seismic mass is important. This location
may be determined by indirect means as a function of the output signal.

Rheological Constitutive Equations. A special constitutive equation
has been found adequate to explain stress relaxation data for a variety of
polymeric materials in simple uniaxial extension over a wide range of
extension ratios. Discrepancies appear, however, when this equation is
applied to equilibrium data on biaxial extensions. In an effort to develop
a more comprehensive expression which will account for the biaxial meas-
urements as well as for the uniaxial ones, a new theory of incompressible
elastic materials was developed. This theory is more general than the usual
ones in that it allows an isotropic pressure to affect the shear. Experiments
on simple extension of rubber strips under varying isotropic pressure indi-
cate that the new theory is indeed germane. Further studies are in prog-
ress to determine whether it will eliminate discrepancies in biaxial data.

In a related study, a test was made of a conjecture originally advanced by
Weissenberg on the equality of certain normal stress components in elastic
fluids. This was a qualitative test to see if direct evidence could be found
by a search for streaming in cross-sectional planes in a fluid flowing through
a pipe of rectangular cross section. The observations showed that the flow
through certain regions of the pipe followed a spiral rather than a straight
line. This evidence indicates that the Weissenberg conjecture does not
hold, a conclusion also reached by Markovitz at Mellon Institute recently
on the basis of certain quantitative measurements of normal stress.

Review of Volume Relaxations in Polymers. A survey of experi-
mental data on volume (dilatational) relaxations in amorphous polymers
was completed. The survey was concerned with the time scale or frequency
of measurement as related to temperature and static pressure. For natural
rubber and poly (vinyl acetate) there are reasonably complete measurements,
principally those made at the Bureau of the dynamic bulk modulus. For
other polymers the data are incomplete and often fragmentary. From the
data available, however, certain generalizations may be made with a reason-
able degree of confidence.

Dilatational relaxations are apparently found in all amorphous poly-
meric systems. The effects of temperature and pressure are qualitatively
the same on the relaxation times associated with dilatation as they are
on those associated with shearing motions. In some cases these effects
are not only similar but are quantitatively identical, indicating in these
cases that the same molecular motions excited by a shearing force are excited
by a pressure.

The data suggest that this identity holds in cases where the molecular
motions involved are solely cooperative motions of segments of the main
chain. The maximum number of segments participating in cooperative
motions in response to a pressure is very much smaller than the maximum
number involved in response to a shear force. This conclusion is supported
by the fact that the relaxation spectrum for dilatation extends over a smaller
range of time than does the relaxation spectrum for shear.

Hypersonic Combustion. Research was continued on the properties
of detonation waves stabilized on a hypervelocity missile in a stationary com-
bustible gas. Wave structure in hydrogen and air was derived on the basis
that a bimolecular reaction controls the rate of heat release behind the shock
frdnt. Effect of heat release in the flow field on wave shape and position was
derived by a graphical and numerical integration of the equations of motion
of the gas between the wave front and missile. The reaction rate constant
was adjusted to yield equality of computed and observed wave shape and posi-
tion over a range of pressures and Mach numbers. Thickness of the detona-
tion wave was derived to be about 104 mean free paths in the shocked gas.
Experimental observations of wave shape and position were also made in
pentane-air and methane-air mixtures.

Two kinds of unstable combustion were observed in these experiments
and in previous experiments with hydrogen. In one kind, the period of the
oscillations was proportional to ignition delay time, suggesting an intermit-
tent combustion at the front of the missile. The second kind was apparently
an acoustic oscillation with period proportional to the sound wave transit
time between the shock and combustion wave fronts.

Reference Fuel Control Test Facilities Operated at the Bureau.
Fuel controls are extremely complicated mechanisms used to control and meter
automatically the fuel flow into gas-turbine aircraft engines under all con-
ditions of flight. These units require extensive adjustment and test prior to
installation to assure optimum aircraft performance. Necessary prerequisites
for the satisfactory adjustment of such units are a high degree of absolute
accuracy in fuel control test benches and standardized test procedures.

The Bureau of Naval Weapons maintains reference fuel control test facil-
ities at the Bureau with which similar equipment used by industry and the
military services may be checked for accuracy. In a typical program, refer-
ence fuel controls are calibrated at the fuel control manufacturer plant, at
the engine manufacturer, and at the Bureau, and standardized test procedures
are agreed upon. After good accuracy agreement is obtained between the
Bureau and industry, the calibrated fuel controls are sent to naval overhaul
stations for accuracy checks of Navy equipment.

The fuel control systems for nearly every model of aviation gas-turbine
in operation in this country have been given these reference tests at the
Bureau. As new engines and new model fuel controls are placed in service
at the rate of about three each year, they are also included in this reference
correlation program.

Static Electric Failure of Aircraft Engine Fuel Hose. Hoses con-
taining an inner core of rubber or other suitable material and an outer
covering of woven wire mesh are used extensively to interconnect the various
fuel system components of internal combustion engines. Improved hoses,
containing an inner core of a relatively nonconductive thermoplastic fluoro-
carbon were developed recently for high-temperature operating conditions.
Many of these failed in service, however, as a result of the generation and
discharge of static electricity produced by the flowing fuel.

Under the sponsorship of the Bureau of Naval Weapons, this phenomenon
is under investigation. Results up to the present time show that very high
electric potentials are produced when a nonconductive liquid flows within a
nonconductive tube or pipe. The potentials are sufficient to produce electric
arcs or sparks several inches long within the tubing. Also, these arcs pene-
trate through the walls of the tubing, resulting in pinhole punctures. Investi-
gations are continuing to determine the influence of the properties of the fuel
on the generation of static electricity, the maximum rate of charge that may
be anticipated under operating conditions, and the desired level of tube
conductivity by which such charges may be conducted safely to the ground.

Electrical spark discharges caused by the flow of a hydrocarbon liquid through
a nonconductive plastic hose. The Bureau is conducting a study aimed at
eliminating service failures in engine fuel lines which occur when the discharges
puncture the line. (See p. 43.)

Reference Tables for a New Thermocouple To Be Established.

Platinel n thermocouples, because of their good stability at intermediate
temperatures, are rapidly gaining acceptance, particularly in the aircraft
industry where base-metal thermocouples, due to exposure to oxidizing high-
temperatures gases, are relatively short-lived. Because of this growing ac-
ceptance, the Bureau has undertaken to establish reference tables for Platinel
II. These tables will be determined from observations on 27 separate thermo-

couples: nine thermocouples from each of three separate melts of materials.
Each group of nine will consist of three each of 20-, 30-, and 40-mil wire.

Concurrently, work is continuing on stability studies in oxidizing atmos-
pheres. It was found that Platinel n is relatively stable at temperatures up
to about 2200 °F.

Flame Speed Inhibitors. Study of the effects of halogenated hydro-
carbons on the flame speed of methane was continued. Halogenated hydro-
carbons have long been used to extinguish fires, and the effects of these sub-
stances on flame speed may possibly be used as a means of testing their
effectiveness. Methyl bromide, methyl chloride, and dichlorofluoromethane
were examined as additives to methane-air mixtures, and of these, methyl
bromide was shown to be the most effective in reducing flame speeds. The
reduction of flame speed was found to be proportional to the amount of
additive.

High'Temperature Thermocouples. Reference tables of thermal
electromotive force versus temperature were completed for three iridium-
fhodium versus iridium thermocouples in current use. Tables for the 40
percent iridium alloy were published and those for the 50 and 60 percent
iridium alloys up to 3900 °F are ready for publication. Computations are
in progress on the data for 10, 25, 75, and 90 percent rhodium for tempera-
tures up to 4000 °F. It is expected that the optimum composition for an
iridium-rhodium versus iridium thermocouple will be derived from the infor-
mation obtained so far on the seven alloys.

2.1.3. ELECTRICITY

The Bureau's work in electricity is primarily the development, improve-
ment, and dissemination of the standards of measurement for electrical
quantities; and the study of the electrical and magnetic properties of ma-
terials. Electrical standards must be established that are constant over long
periods of time, uniform throughout the Nation, and compatible with other
standards used throughout the world. Measurements of electrical quan-
tities directly in terms of length, mass, and time ("absolute measurements")
are extremely difficult and are made only in the realization and confirmation
of electrical standards of resistance, capacitance, inductance, and voltage;
calibration work is done by comparison with these electrical standards.

A new section, Absolute Electrical Measurements, was established to sepa-
rate calibration activity from fundamental measurement research. New pro-
cedures for realizing the electrical units via the volt and henry are being
investigated.

Absolute Measurements. A group of portable 10-picofarad capaci-
tors was built. One capacitor of the group was carried to the National
Research Council (NRC) in Canada for comparison of the units of capaci-
tance maintained in the two countries. Since both NRC and the Bureau
obtain their units of capacitance from calculable standards of the Thompson-
Lampard type, the comparison constituted a check on the accuracy of absolute

44,

X1 X*

One of a group of transport-
able 10-picofarad quartz ca-
pacitors built for use in inter-
comparing NBS capacitance
measurements with those of
other laboratories. One in-
tercomparison has already
been made with the National
Research Council of Canada,
and showed that NBS and
NRC measurements differed
by only 2 parts in ten million.
(See p. 45.)

capacitance measurements at the two laboratories. The comparison indi-
cated that the capacitance units of the two laboratories differed by about two
parts in ten million. Since the Bureau and NRC claim accuracies of only
two or three parts per million, the agreement is much better than was expected.

Considerable progress was made in the development of an improved cal-
culable capacitor. This project is expected to provide a calculable standard
of capacitance accurate to at least one part in ten million.

The inductance analog of the Thompson-Lampard theorem was developed,
and a preliminary study is being made of the practicality of a physical
embodiment.

Continuing studies of the proton precession frequency and the Zeeman
transition frequency indicate a high degree of stability for the ampere, as
maintained at the Bureau with standard resistors and standard cells. Mag-
netic field perturbations in the solenoid used for this work were found respon-
sible for some of the observed measurement fluctuations. A system of
three-dimensional Helmholtz coils was constructed for use in a scheme
expected to greatly reduce these magnetic perturbations.

Impedance of Dry Cells. An extensive study of the impedance char-
acteristics of the most commonly used sizes of Leclanche dry cells and bat-
teries was completed. The impedance was measured by a substitution
method using a Wien bridge. The study covered the frequency range from
50 through 50,000 cycles per second (c/s) to determine changes in the

impedance of dry cells due to aging or use. The impedances of dry cells of
different make, size, type, age, or state of charge vary widely, not only at
a particular frequency but as a function of frequency. In some cases the
impedance tends toward a maximum value at a particular frequency. In
other cases, no maximum value is attained; the impedance increases through-
out a decrease in frequency. Open-circuit voltages and flash currents and
electrical capacities of the cells on standard tests were measured throughout
the study to ascertain possible correlations between these parameters and
impedance and residual capacity.

Battery Depolarizers at High Temperatures. To provide basic in-
formation on the stability of depolarizers (oxidizing agents) used in primary
cells, studies were made of the thermal decomposition of manganese dioxide,
the depolarizer used in the common dry cell, over the range from 440 to
640 °C. Manganese dioxide decomposes to form manganese sesquioxide
and oxygen; the oxygen pressure varies logarithmically with temperature
and reaches 135 atm at 640 °C. At higher temperatures (850 to 980 °C),
the sesquioxide decomposes to form hausmannite and oxygen, with the oxygen
attaining atmospheric pressure at 980 °C. From the measured dependence
of the oxygen pressure on temperature and the known heat capacities of
manganese dioxide, manganese sesquioxide, hausmannite, and oxygen as a
function of temperature, a new value of —228,700 calories was obtained
for the heat of formation of manganese sesquioxide. The data also yielded
a new value of 36.8 cal/deg for the entropy of hausmannite at 25 °C.

Zener Diodes as Voltage Standards, Under a broad measurement
program, the Bureau is investigating methods of accurately measuring the
voltages of zener diodes, which are solid-state devices, in terms of saturated
standard cells having electromotive forces known in absolute electrical
units. Attention focused on the opposition method, wherein the diode
voltage is measured in series opposition to that of standard cells with a
precision of three to four parts per million. Temperature-compensated
diodes having nominal voltages of 8 volts received the most study. As an
adjunct to the measurement program, the Bureau has for two years been
studying the long-range stability of zener diodes. In general, the stability
is an inherent characteristic of the diode and may be affected by operating
conditions and environment.

Membrane Potentials in Fused Salts. Reference electrodes or ref-
erence half-cells for use in electrochemical studies of fused salts are frequently
isolated from the fused salt under study by fused silica or vycor. Apart
from any ionic diffusion that may occur through the silica or vycor, inter-
pretations of the voltages of galvanic cells, including the reference elec-
trodes, may be in error as a result of neglect of potentials that may arise
at the silica or vycor membrane. As part of an investigation to ascertain
the magnitude of these potentials, the Bureau studied membrane potentials
of silica and vycor in silver chloride— sodium chloride melts, maintaining
a constant mole fraction of silver chloride on one side of the membrane but
varying it on the other side. When the mole fraction of silver chloride

was varied from 100 to 10 mole percent on the variable side of a vycor
membrane, the membrane potentials at 850 °C decreased from 540 to 9
millivolts. Thus, for a silver chloride reference electrode, silver chloride
should be used as a minor constituent in a silver chloride-sodium chloride
melt.

Differential A-C— D-C Transfer Standard. A new a-c-d-c com-
parator was developed to meet the growing need for more accurate, as well
as more rapid, means for measuring a-c voltages at audio frequencies. The
instrument can be used for the simultaneous comparison of an unknown a-c
voltage with a known d-c voltage, eliminating the time lag between successive
comparisons necessary with older forms of a-c-d-c transfer instruments that
sometimes changed during the interval. It is ten times as accurate as an
earlier differential voltmeter, although somewhat less convenient to use.

The instrument includes two identical rms voltage-sensing units, with
electrical outputs connected in opposition through a detector. With their
inputs connected to the same power supply, the units are adjusted to equality
of output. They are then connected to the respective external a-c and d-c
sources, with appropriate potentiometer and accessories to measure the
adjustable d-c voltage. When equality of output is again obtained, the volt-
ages of two sources are equal. Drifts and other changes in the units are self-
compensating, so that a usable precision of 10 parts per million (ppm) can
be obtained. The accuracy attainable depends principally on the a-c-d-c
differences of the thermoelement in the a-c unit. Improvements now in
progress in the basic NBS a-c-d-c transfer standards indicate that this differ-
ence is very probably less than 10 ppm from 50 to 2000 c/s and 1 to 500
volts, me frequency and voltage ranges in which there is the greatest demand
for high accuracy.

Magnetism. The nuclear magnetic resonance absorption of Ni61 was
observed in 1 percent Ni61-99 percent Fe and 2 percent Ni61-98 percent Fe
solid solutions at 85.4 Mc/s at room temperature. The line width was about
700 kc/s in the 1-percent sample at room temperature, with some broadening
in the 2-percent sample. At 77 °K the resonance occurred at 89.1 Mc/s with
nearly the same line width as at room temperature. The intensity of the
resonance signal decreased in an externally applied steady magnetic field.
The room temperature hyperfine field at the Ni61 nucleus was 558 kilo-
oersteds (kOe), assuming a nuclear moment of 0.3 nanometer (nm), or 186
kOe, assuming a moment of 0.9 nm. If the hyperfine field at the nickel
nucleus is assumed to be nearly proportional to the local moment, a resonance
frequency of 85.4 Mc/s implies a local atomic magnetic moment of about 2.0
Bohr magnetons at the nickel atom, somewhat less than that in pure iron.

The nuclear magnetic resonance of Ni61 was observed in 1 percent
Ni61-99 percent Co and 2 percent NiG1-98 percent Co alloys. The resonance
frequency was found to be 70.4 Mc/s at room temperature and 71.7 Mc/s at
77 °K. The hyperfine field at nickel in cobalt was about two and one-half
times its value in pure nickel, implying a nearly proportional increase in the

local magnetic moment. The nuclear moment at Ni61 was determined to be
0.70±0.04 nm by nuclear resonance studies in steady external magnetic
fields.

A permanent adjustable standard of magnetic susceptibility was designed
using the magnetic equivalence of a uniformly polarized volume of para-
magnetic material and a solenoid carrying electric current. Such a standard
was incorporated into a magnetic susceptibility bridge in a simple manner,
surrounding the specimen; and the bridge was transformed into an absolute
null instrument of high accuracy and sensitivity, and of great ease and low
cost of construction and operation. By this method numerous particular
advantages of other methods were combined, and some of their notable
limitations were overcome. A preliminary application was made showing
that the bridge performs as expected. A detailed consideration of sources of
error suggests that it may eventually be possible by this method to obtain
greater absolute accuracy than by other known methods.

An apparatus was constructed for determining absolute magnetic suscepti-
bilities down to liquid helium temperatures by both the Thorpe-Senftle and
the Gouy methods. Measurements were made by both methods on powdered
samples of the same batches of (NH4)20sBr6, HgCo(SCN)4, and Fe(NH4)2
(804)2*61120. Comparable accuracies were obtained by the two methods;
however, about 3 X 10"2 as much sample was required for a Thorpe-Senftle
measurement.

Magnetic susceptibility measurements were made on a series of hexachloro-
and hexabromoosmates, M20sX6, and on potassium hexachlororuthenate,
K2RuCl6. The paramagnetism of the Os(iv) complexes is independent of
temperature, and increases as the osmium ions are separated. The magnetic
susceptibility and part of the optical absorption spectrum can be fit to theory
by choosing the values of 2100 ±100 cm-1 for the spin-orbit coupling constant
and 2800±100 cm"1 for the Coulomb interaction coefficient. It is shown
that the effect of dilution is described by the equation x = xoo/(l + Ac? -nx°o ) ,
where x°o is the susceptibility at infinite dilution, d is the average distance
between the osmium ions, A is a constant, and n is approximately 2.

Dielectric Behavior of Liquids and Supercooled Liquids at Ele-
vated Pressures, Apparatus was constructed to study the variation in
dielectric constant and relaxation time of liquids and supercooled liquids at
pressures up to 2000 atm. A specially designed thermostat enables the tem-
perature of the dielectric cell to be accurately controlled and continuously
varied from liquid nitrogen temperature ( — 196 °C) to about 50 °C.

The cell incorporates a novel design feature which permits the density of
the material to be determined simultaneously with the dielectric properties.
Thus, by suitable choice of temperature and pressure, measurements may be
conducted under conditions of constant density in order to provide more
definitive tests of dielectric theory. Measurements on a series of alkyl
halides are planned to examine the correlation between dielectric relaxation
and the liquid free volume.

Dielectric measurements on materials under high pressures provide a means for
testing dielectric theory. (See p. 48.)

Precision Measurement of the Dielectric Constant of Solid Bodies,

A new three-terminal dielectric cell was completed and used to make precise
dielectric constant measurements by the two-fluid method, which does not
require electrodes on the specimen. A special specimen of fused silica was
prepared to check the method. The excellent results obtained showed that
the dielectric constant of a well-made disk specimen can be obtained to within
better than 200 ppm between 100 c/s and 50 kc/s.

In connection with this program, the guard gap correction was examined
theoretically. This correction allows the effective area of a three-terminal
electrode to be calculated with high precision.

The techniques of preparing dielectric specimens of polymeric materials
were improved to the extent that disk specimens 8 cm in diameter can be
prepared with a variation in thickness of only about 5 /x. This improvement
is mainly the result of better control in use of the well-known Schieffer abrasion
machine. Such accurate control of thickness is important in the precision
of dielectric measurements.

Humidity -Time Studies of Dielectric Constant and Loss Index,
In this continuing program, the dielectric constant and the loss index of a
material were measured as functions of time after an initial abrupt change
from less than 1.5 percent humidity to 52 percent humidity, or the reverse.
Because of advanced developments allowing precision dielectric measure-
ments without specimen electrodes, specimens without metal electrodes were
measured and preliminary results obtained. Measurements are in progress
on polystyrene, polyethylene, polycarbonate, polytetrafluoroethylene and its
copolymers, and poly (1,4 cyclohexylenedimethylene terephthalate) .

Theoretical Studies on Dielectrics. Theoretical work was completed
on the relaxation spectrum of an Ising lattice with dipole-dipole interaction.
In the simplest approximation with no interaction, such a lattice gives a
single dielectric relaxation time. The present calculations show that dipole-
dipole interaction leads not only to the anticipated principal relaxation time,
but also to a set of shorter relaxaton times of lower intensity.

Chain-Folding in Polymer Crystals. Linear highly crystallizable
polymers tend to crystallize in thin crystals (lamellae) having upper and
lower surfaces that consist of chain folds. The polymer chain axes are
perpendicular to the large flat surfaces. Such crystals are of great importance
to understanding the mechanical and dielectric properties of semicrystalline
polymers.

A detailed theoretical analysis of chain-folding in polymer crystals was
made from the viewpoint of nucleation and growth theory. Fluctuations
of fold length that occur during the growth of a layer were taken into account.
The results cast some doubt on the existence of a "transition" in the growth
rate near the melting point as predicted elsewhere. In certain limiting
cases, the theory gives the same results as a simplified theory published
earlier. In particular, the critical nucleus length fairly near the melting
point is given by l*g = 2(je/Af-\-kT/boo: Because A/ varies as AT, the
degree of supercooling, V0 tends to increase with rising growth temperature.
(kT/b0(T is small compared to 2<re/A/.) A transition does actually take place
in the growth rate at low temperatures (high supercooling), but this is not
expected to be observable in most polymers.

The surface free energies, o>, of the chain-folded surfaces of polyethylene
and polychlorotrifluoroethylene were estimated by both thermodynamic and
kinetic methods. For polyethylene, o-e is about 60 erg/cm2; and for poly-
chlorotrifluoroethylene, 35 erg/cm2. Lateral surface free energies, a, have
also been estimated.

An experimental investigation of the change of thickness of chain-folded
lamellae on storage at constant temperature was recently completed. The
lamellae were found to thicken slowly on storage according to {t) = £* + #
log[(£ — 10) /t0], where (t — 10) is the age of a lamellar crystal and t0, a
time that is generally much smaller than (t, — t0). In polyethylene, B ranges
from about 45 to 65 A per decade of time, depending on the temperature.
A theory that explains most of this isothermal thickening effect was devised,
giving B values in the range studied experimentally.

Dielectric Properties of Polymers. As part of the continuing pro-
gram on the electrical properties of polymers, the dielectric properties ,of the
new and interesting polycarbonate polymers are being measured over wide
ranges of frequency and temperature. In general, the pattern set by the
earlier complete study on polychlorotrifluoroethylene is being emphasized.
Dielectric Properties of Dipolar Chain Compounds. The dipolar
derivatives of the rc-alkanes (e.g., Ai-bromides, rc-alcohols, and esters) behave
as simple single-axis rotators in a crystalline field. In many cases, a state
of hindered rotation appears abruptly at a sharp transition temperature in

the crystal (rotational phase transition) . Dielectric studies on these materials
provide a check on theories of dielectric constant and loss, and also give in-
teresting information on the rotational phase transition. The rate of rotation
is often very rapid, corresponding to dielectric relaxation times of 10~7 to 10"10
seconds. Work proceeded on instrumentation aimed at making accurate
dielectric measurements in the 10 to 1000 Mc/s region on esters, bromides,
and similar materials.

Molecules with spherical or near-spherical symmetry, such as CH3 — C — Cl3
(methyl chloroform) , also exhibit molecular rotation in the solid state.
Dielectric studies on this class of materials are in progress.

Microwave Absorption in Compressed Gases, A systematic study
of the nonresonant (relaxation) spectra of a number of gases consisting of
symmetric top molecules (e.g., CH3C1 and CH3CN) in a variety of nonpolar
foreign gas mixtures was completed. Well over 100 systems have been
examined during the past year. Since the relaxation times are governed
simply by bimolecular collisions at the densities in question, these data
yield effective collision cross sections for molecular reorientation. With
development of the theoretical interpretation of these cross sections now in
progress, this work should provide a new and versatile method of studying
intermolecular forces, especially the anisotropic contribution.

These 200-cm spheres
were used to study
sparkover voltages.
Results were in sub-
stantial agreement
with international
sphere-gap tables.
The range of 30- to
75-cm spacings be-
tween the spheres rep-
resented a voltage
range of 750 to 1550
kv. (Seep. 52.)

High Voltage, A study has been completed of the negative impulse
sparkover voltages for 200-cm spheres at spacings from 30 to 75 cm over
the voltage range from 750 to 1550 kilovolts (kv). The results obtained
were in substantial agreement with currently accepted international sphere
gap tables-
Other activities of a consolidating or preparatory nature included work
on the 350-kv instrument transformer, the "Mighty Pike," for the Ontario
Hydro Electric Power Commission. Work on the design of a compressed
gas capacitor to replace the "Mighty Pike" represented further consolidation
of this program for using capacitance dividers in voltage transformer cali-
brations. A second high-voltage d-c resistor was constructed to extend the
range of our direct-voltage measurement capabilities.

Most effort in the program to develop improved techniques for the cali-
bration of inductive voltage dividers, as well as in the joint effort within
the Bureau in developing impulse voltage and current measuring techniques
of importance in the study of exploding wire phenomena, has been directed
toward the design, construction, and evaluation of equipment.

2.1.4. RADIO STANDARDS

The Radio Standards Laboratory is responsible for providing the central
basis for electromagnetic measurements above 30 kc/s in the United States
and for assuring international coordination of such measurements. The
laboratory conducts basic research on physical principles and fundamental
engineering techniques which have applications in the field of radio science.
This research leads to the establishment, maintenance, continued improve-
ment, and international coordination of a comprehensive set of national
standards and precision measurement techniques for fundamental electro-
magnetic quantities. Extensive contact is maintained with other govern-
ment agencies and with industry to keep pace with scientific trends which
will establish future measurement requirements and to disseminate infor-
mation concerning precision electromagnetic measurements.

In addition to the national standards, this laboratory provides new theories
which radio scientists can exploit, new measuring devices which the instru-
ment industry can produce, accurate design data for radio materials, cali-
bration and broadcast services which furnish standards of radio measure-
ment to hundreds of industrial and Government laboratories over the country,
and consultation and instruction to assist other laboratories in the solution
of problems in this field.

To better pinpoint the connection between measurement accuracies and the
performance of major radio-electronic systems, the laboratory has begun a
series of seminars in which speakers from industry are invited for one- or
two-day meetings with laboratory personnel. Three seminars have been held
so far and the results have proved very helpful in clarifying needs and
priorities.

Because of the continued and increasing demands for electromagnetic
measurement services, considerable work was done during the year in defining
long-range plans for the Radio Standards Laboratory. Most of this informa-
tion was presented in extensive series of tables and charts which outline the
measurement and calibration capabilities now available and those which
might be furnished within five years. Also, with the aid of a special appro-
priation, design work began on a new multi-million dollar building for the
Radio Standards Laboratory.

Theoretical Physics. The far field of an antenna radiating into a
half space may, in principle, be obtained from the two-dimensional Fourier
transform of near-field values. However, the measurement of the near field
may be affected in a complicated way by the characteristics of the measuring
antenna. The theory was developed of a measuring antenna of arbitrary but
known characteristics, under the assumption that multiple reflections be-
tween the measured and the measuring antenna are negligible. This work
was motivated by a need for precise, inside-the-laboratory measurements on
an electrically large aperture antenna in a microwave Michelson inter-
ferometer, but the results may be of wider interest.

In connection with the plasma physics program, correction terms to the
equation-of-state of an ionized gas were obtained via new methods of quantum
statistical mechanics. These results have led to a better understanding of
the role of the basic particle interactions in a plasma.

RADIO STANDARDS PHYSICS

The Bureau's program in radio standards physics furthers the precise and
fundamental study of physical constants and matter relating to radio science.
It also establishes uniform, accurate standards of measurement in areas of
frequency, time, and material properties, and disseminates these standards
to the general public. The work is, for the most part, dictated by the re-
quirements of the rapidly expanding electronic and space industries and
makes possible a greater accuracy of performance by both private and
Government agencies. The staff provides a readily available consulting
service to industry, Government agencies, and individuals.

Fort Collins Standard Radio Transmitting Site. Construction is
practically completed on the new facility at Fort Collins, Colo., which provides
a transmission of standard low frequency (LF) and very low frequency
(VLF) carrier signals with high phase stability. On July 5, 1963,
the low-frequency station WWVB (60 kc/s) began transmitting from the
new site near Fort Collins, Colo., with a radiated power of several kilowatts
and with the carrier phase locked to the U.S. Working Frequency Standard.
Time signals will be added and the carrier power will be increased within
the next few months. Measurements near Los Angeles, Calif., and Chat-
tanooga, Tenn., gave values of received field strength of about 150 and 100
microvolts per meter, respectively. Station WWVL (20 kc/s) began operat-
ing at the new site during the late summer. This station provides standard
frequency signals and will serve as an experimental facility to develop tech-

View from halfway up one of the 400-foot towers supporting antennas for the
new LF and VLF standard frequency transmitting stations at Fort Collins, Colo.
The "helix house" (center foreground) contains the helical tuning device for
the antenna. Furrows show the grid pattern of the ground wires. (See p. 53.)

niques using narrow-band signals to provide means for clock synchronization
from a single station over wide areas of the world. The facility will also
enable the Bureau to accelerate additional research, development, and services
related to LF and VLF frequency and time broadcasts. Because of the high
phase stability of LF and VLF signals, these broadcasts provide wide dis-
semination of frequency and time standards with a high degree of received
accuracy. A large part of the cost of the 20-kc/s station was provided by
the National Aeronautics and Space Administration.

WWVB and WWVL will not replace the shortwave transmissions of WWV
and WWVH. The high-frequency signals require only simple receivers and
their accuracy is sufficient to meet the needs of television and radio stations,
electric power companies, amateurs, many businesses, and the general public.
Atomic Frequency Standard Research. A new cesium beam fre-
quency standard, NBS (III), has been completed. The spectral line width
attained with this instrument is less than one-half (and the precision should
therefore be about twice) that of NBS II. The NBS I cesium beam was con-
verted to a thallium beam for the purpose of evaluating a thallium transition
as the standard of frequency. Approximately the same precision is being
attained with thallium as with cesium and it appears that an improvement of
one order of magnitude in accuracy over that of cesium can be expected. A
hydrogen maser, which is under construction, will also be evaluated as a
primary frequency standard.

An NBS atomic time scale was established which uses the United States
Frequency Standard as a basis. NBS atomic time was related to time pulses
of WWV, to the atomic time kept by the Naval Observatory (A 1 Time) , and
to the time pulses of the Loran-C master station at Cape Fear, N.C. This

relation was determined to 5 microseconds by carrying a high-precision,
quartz-oscillator clock from Boulder to these three stations. This comparison
technique also gives the propagation delays between these three stations so
that absolute time comparisons may be made continuously by means of
propagated signals.

Theoretical work has been completed on the effects of high-intensity electro-
magnetic fields on atomic systems and the related effects of multiple quantum
jumps, the Bloch-Siegert frequency shift, and frequency shifts due to the
presence of a third state. Frequency shifts caused by the presence of addi-
tional signals in the excitation radiation have also been calculated theo-
retically.

Quantum Electronics, Research in progress in this area includes the
measurement of the velocity of gamma-rays by means of the Mossbauer effect,
the measurement of the fine structure constant by determining the fine struc-
ture separation in singly ionized helium, and a study of the various mecha-
nisms of inducing blue fluorescence in anthracene with the red light of a
"giant pulsed" ruby laser. Calculations have been completed on the inter-
mediate field Stark effect in symmetric top molecules.

This new cesium beam frequency standard (which can also be used with thal-
lium) is now being evaluated. Its length of 18 feet is about 8 feet longer than
earlier models. This added length should significantly increase the precision.
(Seep. 54.)

714-691 0—64 5

Radio and Microwave Materials, Materials research is designed to
acquire an understanding of the magnetic (primarily ferrimagnetic), di-
electric, and conductive behavior of materials at radio and microwave fre-
quencies in terms of the atomic constitution and structure of matter, and to
improve and develop standards and measuring techniques for determining
material properties.

Magnetics. The change of elastic modulus with magnetization was in-
vestigated in a number of ferrites. The elastic modules first decreases and
then increases with increasing external field for all of the ferrites investigated.
This is a new result and is similar to behavior observed in nickel when
measured by static methods but not when dynamic methods are used. The
decrease in the static modules is attributed to domain wall stiffness and a
theory relating the two was developed. Fair quantitative agreement was found
between the experimental observations and the predictions of the theory.
Time-dependent demagnetization effects were also investigated for a number
of ferrites. A rather low temperature coefficient of permeability as well as
an anomalous disaccommodation effect were observed in a cobalt substituted
specimen. The ferrite specimens of controlled composition which were used
in these investigations were prepared by the NBS materials synthesis group.

Further improvements in initial permeability-measuring technology made
it possible to cover the magnetic spectrum at radiofrequencies using only the
permeameter and a versatile variable-length cavity. Studies of the deter-
mination of gyromagnetic ratio and line width of polycrystalline ferrites
showed that disk-shaped samples in rectangular TE102 cavities at L-band
frequencies can be used in the same way as spherical samples are used at
higher frequencies. It appears that the disk technique is the best method to
determine the gyromagnetic ratio and line width at these frequencies. How-
ever, it is necessary to utilize demagnetization corrections even for very thin
disks, as was determined from an extensive study of ferrimagnetic resonance
properties as a function of aspect ratio. This indicates that numerous previ-
ous disk measurements may be in considerable error. The study of the disk
technique was supported in part by the Navy.

A study of the mathematical representation of the complex tensor perme-
ability was begun and quickly led to a basic investigation of ferrimagnetic
resonance (FMR), especially of losses which may be related to spin waves,
because FMR losses determine the line shape of the resonance and these
losses in turn are often determined by spin wave effects. Two new and im-
portant methods have been evolved for studying the FMR loss versus coupling
to the spin wave spectrum. In one, resonant ellipsoids of various ellipticities
and orientations are used. The other requires intrinsic magnetic measure-
ments at resonance and away from resonance on only one specimen shape
(rod or sphere). Computer programs were prepared for correlating ellip-
soidal data with intrinsic data. A roundrobin among various government
and industrial laboratories was conducted on FMR and permittivity of 10
ferrite compositions.

Magnetic resonance techniques are used to determine the magnetic energy
levels, relaxation times, and transition probabilities of paramagnetic and
anti-paramagnetic crystals. Thorough studies were made of the electron
paramagnetic resonance (EPR) spectrum of a natural amethyst single crystal.
The spectrum is extremely complicated and resists analysis by the usual
crystal field methods; however, some information on the field splitting and
the species of the ions was obtained. An important observation is that
bleaching out of the purple color of the amethyst left the EPR spectrum es-
sentially unchanged. The EPR spectrum of iron-doped synthetic quartz is
also being investigated. A new method of comparing .Z-band and £-band
cylindrical cavities for EPR work was developed.

Dielectrics. National and international roundrobin dielectric measure-
ments were undertaken to help establish the present limits of accuracy for
such measurements. High-temperature dielectric measurements received
further attention, and the importance of this was emphasized by the meeting
of an ad hoc committee representing 10 interested laboratories. Standard
reference samples were further studied, resulting in selection of two glass
compositions as standard materials for microwave frequencies. An available
second-order perturbation theory for computing the permittivity of various
samples in a resonator was investigated and gave rather accurate results.
Preliminary results were obtained on the measurement of the dielectric con-
stant of small spheres. Complex arguments become necessary for very lossy
materials when expressing the complex dielectric properties of a material
using complex propagation factors. A computer program was prepared for
cavity techniques to be used in investigating lossy materials.

Mathematical investigations were undertaken of the feasibility of calculat-
ing permittivity and permeability of crystals based on their structure.
Preliminary results are promising.

Conductivity. Whiskers of pure nickel of considerable length were pre-
pared for the first time. Copper whiskers have also been prepared. Since
whiskers are close to being "one-dimensional" single crystals, they are espe-
cially valuable for studying the effects of the surface on their electrical and
magnetic behavior. Nickel-halide platelets have also been grown.

Materials Synthesis. Ilmenite-hematite solid solutions were studied by
characterizing the dielectric and magnetic properties of the solid solution
series Ni^Mn/TiOg-FesOg. The electromagnetic properties of this system
resemble those of the ferrites.

Plasma. A quantitative understanding of the basic physics of atoms
and molecules in a high planetary atmosphere (essentially a plasma) is nec-
essary for progress in physical interpretation of experiments and observations
performed in these atmospheres. Such understanding is vital to the solution
of basic problems of astrophysics and to the design, for example, of adequate
systems of radio communications between earth and experimental vehicles.

During the past year observations of the magnetoresistance of plasmas were
made, utilizing both plane-parallel and cylindrical electrode structures. The
data agree in part with the theory, but the theory is suspect in the pressure

range in which magnetoresistance was observed. This work was supported
in part by the Advanced Research Projects Agency of the Department of
Defense.

Microwave Interactions With Plasma. Fast, accurate, and conven-
ient diagnostic techniques are necessary to the understanding of processes
of formation and loss of plasmas. A knowledge of such processes in turn
permits the utilization of the plasmas as tools of the microwave and propaga-
tion engineer.

The surface wave diagnostic technique is being used to investigate non-
linear diffusion processes in a plasma in which the principal loss mechanism
is wall recombination. The basic technique is being extended to a time-
resolved measurement in order to look into the thermalized afterglow of a
discharge. A Laplace transform technique has been developed to facilitate
the spatial resolution of electron density in the surface wave determination.

Speed of Light (Diffraction Correction). During the year the ef-
fort applied to this problem was largely devoted to analysis and computation
relating to the diffraction correction for the determination of the speed of
light with a microwave Michelson interferometer. It was shown that (1)
evanescent waves, (2) accidental mirror tilt, (3) variation of reflection
coefficient of the mirror with angle of incidence, and (4) the component of
the transverse electric aperture field perpendicular to the nominal direction
of the field have no significant effect upon the diffraction correction.

Some speed of light measurements have been made with encouraging
results. The standard deviation of a single measurement is of the order of
0.2 to 0.3 km/sec. It is expected that this deviation can be improved sig-
nificantly for the final measurements.

Final tests are being conducted on this Michelson interferometer prior to meas-
uring the speed of light at millimeter wavelengths. (See p. 58.)

Stark Voltmeter. The splitting of spectral lines due to the applica-
tion of an electric field, which is called the Stark effect, offers an attractive
possibility for measuring high voltages with high precision. During the year
an apparatus employing this principle has been undergoing preliminary tests
at voltages up to 5000 volts. This apparatus employs a Fabry-Perot resonator
as an absorption cell for the observation of a rotational transition of methyl
cyanide at 37 Gc/s. Short-time precisions of 1 or 2 parts in 10,000 have
been obtained. In the next year the present, relatively crude, electronic
circuitry will be replaced and other improvements will be made with the
expectation that the precision will be improved by one or two orders of
magnitude, as allowed by the theoretical limitations of the method.

RADIO STANDARDS ENGINEERING

The Bureau's program in radio standards engineering includes basic re-
search on physical principles and fundamental engineering techniques having
applications in the field of precision electromagnetic measurements. This
research leads to the establishment, maintenance, continued improvement,
and international coordination of a comprehensive set of national standards
and precision measurement techniques for fundamental electromagnetic
quantities in radio circuits. Dissemination of measurement accuracy is
accomplished in large part through calibration services, and information on
precision electromagnetic measurements is disseminated widely through
publication, consultation, conference papers, invited talks, committee work
with technical societies, individual visits to other laboratories, and the NBS-
Air Force Working Group visits to Air Force contractors.

Low-Frequency Calibration. New instrumentation for the rapid cali-
bration of volt boxes has been virtually completed. In the calibration of a
number of units, this new console has reduced uncertainties resulting from
random errors. All critical indications in the console are either digital or
null-indicating, and all preliminary computations are performed automatically
by a computer in the console. The operator needs only to add the data which
are entered directly on a calculator.

The high-voltage facility now offers steady-state calibrations up to 50
kilovolts (kv) with an uncertainty less than ±0.01 percent using direct
current. Alternating-current calibrations up to 13.2 kv, with an uncertainty
less than ±0.2 percent at 60 or 400 c/s, can also be performed. The recent
completion of a grounded safety enclosure and control console adds to the
convenience of measurement and the safety of personnel.

The internal loading errors in inductive voltage dividers of a specific design
were analyzed to provide a basis for the construction of 10- and 20-section
dividers having known relative errors. A method of complementary measure-
ments has been developed for the absolute measurement of certain nonzero
errors in these dividers. The goal of this work, which is still in the experi-
mental state, is a simple method for the accurate absolute establishment of
alternating-voltage ratio over a wide frequency range.

Portions of the Wenner precision bridge have been insulated with Teflon
and satisfactory measurements at 25 °C can now be made on 1 -megohm
standard resistors.

A new standard cell calibration console incorporates facilities for standard
cell comparison and temperature determination of the regulated oil baths.
By using both a microvolt potentiometer and a specially modified sensitive
standard cell comparator, two operators at the console can measure inde-
pendently and simultaneously the electromotive forces of standard cells.

High-Frequency Standards and Calibration, A method has been
developed for calibrating high-frequency incremental air capacitors to an
accuracy within 0.1 percent (limited mainly by their low-frequency calibra-
tion accuracy). In conjunction with this technique a dual twin-T high-
frequency bridge is being constructed, and mathematical study indicates
that the circuit constants may be adequately evaluated by using only cali-
brated capacitors. The basic accuracy of this bridge will then be limited
by the accuracy of the incremental capacitors used in its calibration.

The assembly of an ultra-high-frequency coaxial reflectometer has been
brought nearly to completion by the design and construction of a symmetrical
four-port directional coupler and a coaxial tuner of incremental capacitance
and constant inductance. An interesting sidelight, also in the coaxial field,
is that according to measurements made by the laboratory the open-circuit
fringing capacitance for a precision % X i/2 inch air line, measured by a
three-terminal method, is over 10 percent less than the computed value found
in the literature.

Given conductors of any complicated shape, with uniform current density
(direct current), their self -inductances and mutual inductance can now be
calculated exactly from equations developed by the laboratory. This work
has been extended to the high radiofrequencies with an approximating tech-
nique for evaluating the resistance and inductance of conductors with less
complicated shapes. Using a high-speed computer, this method yields high
accuracies.

By modifying the design of radiofrequency (rf) -voltage bolometer bridge
mounts the accuracy of 300 to 1000 Mc/s sinusoidal unbalanced voltage
measurements were improved from within ±5 percent to within ±1 percent
based upon comparison with power measurements. Promising results were
also obtained in extending the frequency upward, with accuracies of about
10 percent at 2000 Mc/s. Extension of calibration services is subject to
development of stable interlaboratory standards and further verification.

Development of a balanced continuous wave (cw) rf voltage, and an rf
current standard and associated measurement techniques, was nearly com-
pleted for frequencies to 1000 Mc/s. These are to be incorporated in NBS
field-strength standards which are expected to be completed for these fre-
quencies during 1964.

A noise power comparator system, designed to measure noise power from
10-18 to 10"21 watts with a precision of at least 0.02 percent, has been as-
sembled and is undergoing preliminary tests. This improvement in sensitivity

and precision is expected through the use of a two channel radiometer (in-
stead of the usual single-channel device) which has been developed by the
staff.

Several types of very-high-precision noise sources are being developed to
cover the needs of (1) high-level sources (up to 30,000 °K equivalent noise
temperature), (2) moderate-level sources (equivalent noise temperatures
within a few hundred degrees of room temperature), (3) low-level sources
(equivalent noise temperature to 77 °K or lower), (4) variable impedance
sources, and (5) ultra-high-precision, constant power, invariant impedance
sources. Reference sources using emission-stabilized temperature-limited
diodes and temperature-stabilized impedance networks in oil baths and
furnaces have been constructed. Evaluation of these sources is in progress.

A mode filter was constructed for use in a 3.2-in.-diameter waveguide-
below-cutoff attenuator. The filter attenuates the undesired TM0i mode by
98 decibels (db) and attenuates the desired TEn mode by only 0.2 db.

Significant progress has been made in the development of temperature-
stable thin-film resistive elements. The elements are made by the vacuum
evaporation of a combination of metallic alloys. By proper control of
fabrication parameters, the resistors are stable with full power dissipation
under ambient conditions of 200 °C. The temperature coefficient can be con-
trolled to values less than 50 ppm/°C. Resistors have been fabricated with
values up to 350 ohms per square, and work is in progress to determine the
maximum value obtainable.

The accuracy of rf voltage calibrations up to 30 Mc/s was improved by
one order of magnitude, to within approximately 0.1 percent. This was
achieved through improvements in the national reference standard and the
installation of thermal voltage converters as working standards. Precision
of measurement in the microvolt region was improved by one order of
magnitude by installing new detecting devices in the microvolt calibrator.

New and extended high-frequency impedance calibration services include
three-terminal capacitance at 100 kc/s, 465 kc/s, and 1 Mc/s for values rang-
ing from 0.01 to 100 picofarads (pf), and the extension of coaxial measure-
ments to frequencies as high as 1 Gc/s. In the area of primary standards,
a computer program has been completed which yields the exact characteristic
impedance of a coaxial line as a function of frequency. The computer pro-
gram provides rapid evaluation and incorporates the Bessel functions for the
corrections arising from the skin depth of current penetration.

In high-frequency attenuation, the upper frequency limit has been increased
from 5.6 to 10 Gc/s, and the accuracy from 0.3 to 4 Gc/s has been increased
from 0.1 db/10 to 0.05 db/10 over a 40-db measurement range. The calibra-
tion accuracies of loop antennas, in field-strength studies, have been improved
from 5 percent to approximately 1 or 2 percent at frequencies up to 30 Mc/s.
This is being accomplished by utilizing both "standard field" and "standard
antenna" techniques. The frequency range of dipole antenna calibrations
has been extended to 500 Mc/s.

Microwave Standards and Calibration. The international compari-
son of low-power microwave standards, begun in 1957, is being continued
and, during 1963, Japanese measurements on NBS mounts agreed with NBS
measurements to well within experimental error (0.5 percent) . Improve-
ments of the NBS facilities (current maximum error = 0.2 percent), through
reduction of noncomputable rf losses, were continued. Calibration service
is being extended to other frequency bands.

The design of a microwave high-power calorimeter is well advanced.
Testing and error analyses of the calorimeter and of an electron beam power
meter is being continued. A subtle but important error associated with the
use of the latter device has been discovered and analyzed. This error arises
through the effect of the thermal velocity distribution in the electron beam
on the magnitude of the reference current.

In recent years, the laboratory has offered reflection coefficient calibration
services in several rectangular waveguide sizes. During the past year em-
phasis has been placed on extending these services to coaxial components.
A thorough study of available coaxial connectors has identified two designs,
one a commercial design and one the NBS-Woods design, either of which
when assembled according to specifications contributes a reflection coefficient
of less than 0.005 ( VSWR less than 1.01) .

Two reflectometer systems have been developed for measurements on
coaxial devices — one is a hybrid system comprised of a coaxial precision
line and associated elements appended to a rectangular waveguide reflec-
tometer through a coax-to-waveguide adapter; the other is an all-coaxial
system. The hybrid system has been thoroughly tested and has an accuracy
equivalent to the existing waveguide systems. Components for the all-coaxial
system have been developed and carefully tested. Their performance indi-
cates that an all-coaxial reflectometer with an accuracy equivalent to exist-
ing reflectometers is possible, but tests must still be made on the total sys-
tem. At wavelengths exceeding about 10 cm, the all-coaxial system will
occupy less space than the hybrid system.

Development of a phase-shift-measuring system, utilizing a sliding short
circuit as a standard, and capable of measuring phase shift to an accuracy of
0.01 degree, has been completed. This system has been thoroughly tested
and is now ready for development as a national microwave phase-shift cali-
bration service.

The development of the modulated subcarrier technique of attenuation
measurement culminated during the year with the completion and submission
of papers describing detailed analyses of the components. A system was
constructed for study in the calibration center. Among the advantages
offered by the modulated subcarrier technique of attenuation measurement
are (1) only one oscillator is required, (2) relatively inexpensive but highly
accurate audio voltage transformers can be used as attenuation standards,
(3) phase information is readily obtainable with the same system, and (4)
deviation of the detector from linearity becomes significant at higher power
levels than in the case of the intermediate frequency (IF) system.

The development of millimeter-wave technology in recent years has extended
the spectrum of useful frequencies, and the present rapid development of
infrared and optical coherent sources presages a range of useful frequencies
which will exceed by many times the range available now. Increasing effort,
therefore, is being diverted to meet the demand for standards over this
vast frequency range. A variety of components for use at approximately
40 and 70 Gc/s and part of a system for use at approximately 150 Gc/s
have been acquired. A conventional 69.810-Gc/s reflectometer has been
constructed and is undergoing tests. The sources have been phase-locked to
the sixth harmonic of a phase-stabilized Z-band generator, and an encourag-
ing preliminary performance study of the millimeter wave reflectometer has
been made.

A heterodyne receiver employing a phase-stabilized local oscillator has
been provided for reflection coefficient and attenuation measurements at
69.810 Gc/s and a method is being developed for the measurement of milli-
meter wave power at about the one-watt level.

For microwave horn gain calibrations in the absence of "darkroom" facili-
ties, a nanosecond (nsec) pulse technique has been developed. Tests using
available components have shown that the system in its present state of de-
velopment, employing 40-nsec pulses in a clear volume 60 ft X 60 ft X 20 ft,
would be capable of an accuracy within 1 percent providing corrections
could be made for any dispersion and bandwidth limitations of the horns
to be calibrated. Application of the technique to waveform analysis is
being considered.

The development of a calibration system which uses a transfer method of
comparing bolometric power-measuring devices has led to a new calibra-
tion service for low-level cw power measurements in the frequency range
of 12.4 to 18.0 Gc/s (WR62 waveguide) . This system is the first in a series
of microwave power calibration systems which are under development to
utilize this method in the higher microwave region. During this develop-
mental work, the implementation and procedure of this transfer method
have been considerably simplified; it is expected that further refinements
will be achieved as the work progresses.

The use of a new material for the hot-body source in the United States
National Standard of microwave noise has resulted in considerable improve-
ment in the operation of this standard and reduced the time required to
stabilize the system to about one-fourth that which was previously necessary.
The material, silicon carbide imbeded in beryllium oxide, was selected after
study and experimentation with various possible materials.

Further work on the waveguide rotary-vane attenuator revealed an addi-
tional vane-displacement error caused by eccentricity and backlash of the
mechanical gear train. Analysis has led to a precise method of specifying
this systematic error. With this knowledge, the rotary-vane attenuator can
now be used more accurately, and thus it might be that this attenuator
will be useful as an rf attenuation standard.

A new transfer instrument, designed and built by the Bureau, is used for the
intercomparison of microwave power meters. A bolometer unit is being cali-
brated. The insulated chamber (which is normally closed) stabilizes the
temperature around the equipment. (See p. 64.)

A new approach to the fabrication of precision rectangular waveguide,
in connection with the development of reflection calibration systems in
several waveguide sizes, has resulted in improved accuracy of calibration
for small values of reflection coefficient. The method consists of a "gage-
block type" construction which allows partial adjustment to an exact rec-
tangular shape, and it has provided a precision waveguide section in WR90
waveguide (8.2 to 12.4 Gc/s) with internal dimensions approaching a toler-
ance of ±0.00005 in. and a precision waveguide section in WR62 waveguide
( 12.4 to 18.0 Gc/s) with a tolerance better than ± 0.00005 in.

Fabry-Perot Interferometer Used as a Dilatometer. A dilatom-
eter which measures linear displacements as small as 10~7 cm has been
developed. This instrument, based on the principle of the Fabry-Perot
interferometer, is being used in studies of the static strain resulting from the
magnetization of ferrites. It can also be used to determine the strains en-
countered in thermal expansions, the piezoelectric effect, or other phenomena
in which the strains are similar in magnitude. Work on the dilatometer was
sponsored jointly by the Army and the Navy.

In the interferometer, the specimen whose dimensional change is being
determined is held firmly between an adjustable tailstock and a moveable
table on which is mounted one mirror of the interferometer. A telescope,
having a micrometer eyepiece for the determination of the change in diam-
eter of the fringes, is used to form the interference pattern- When a strain

is induced in the specimen, the resultant movement of the mirror is detected
as a change in diameter of one of the rings in the fringe pattern.

Using a mercury 198 light source, a mirror separation of 2.5 mm, and a
telescope with a focal length of 25 cm, the magnification of the instrument is
of the order of 10,000. For example, if the mirror moves 10~7 cm, the ring
diameter changes by 10-3 cm, a change which can easily be measured.

2.1.5. HEAT

Heat measurements, standards, and related research play a most important
role in modern science and technology. The Bureau discharges important
responsibilities in these areas through the maintenance of the National
standards for such heat measurements as thermal diffusivity, heat capacity,
and heat of combustion. Internationally agreed upon temperature standards
are maintained to assure a common scale upon which all temperature meas-
urements are based. A strong research program aims to keep these standards
adequate for the expanding scientific needs. In addition, supporting re-
search on the physical properties of solids and gases at both low and high
temperatures includes studies in low-temperature physics, statistical thermo-
dynamics, high-temperature processes, high-pressure thermodynamics, and in
various aspects of plasma physics.

An automatic thermocouple comparator has been put into operation, with
substantial resultant increases in efficiency and reliability of the calibration
procedure. Computer programs have been developed for analyzing low-
temperature heat-capacity data and for calculating the thermal functions.
The kinetics of a dissociation reaction have been established by combining
shock wave techniques with time-resolved absorption spectrophotometry. A
detailed calculation of the thermodynamic properties of ionized gases at high
temperatures has been completed.

Molecular Energy Levels Program. The major effort in this pro-
gram, which is supported in part by the National Aeronautics and Space
Administration, is directed toward the accurate determination of the energy
levels of small molecules. Information of this kind is of fundamental im-
portance to the interpretation and understanding of phenomena that occur
in environments at extreme temperatures or which are inaccessible, such as
electric discharges, flames, the upper atmosphere, comets, and stars.

Recent work has emphasized the observation and measurement of the
spectra of diatomic molecules in the vacuum ultraviolet region, from 1100
to 2500 angstroms (A). The properties of the long-lived afterglows from
electric discharges through nitrogen have been investigated in the vacuum
ultraviolet. The spectra indicate that substantial numbers of very highly
energetic nitrogen molecules emerge from the discharge region and retain
their energy for long periods of time. The unusual conditions existing in
certain regions of the afterglow have permitted observations of many vibra-
tional states of the nitrogen molecule not previously detected.

An apparatus has been constructed for observing the vacuum ultraviolet
absorption spectra of transient species produced by the flash photolysis of

gases. By using a flash lamp to produce a high-intensity, short-duration
continuum it is possible to record absorption spectra of transient species
from 1100 to 3500 A, with time resolution as short as 10 microseconds.

Plasma Transport Processes, An apparatus for operating a mag-
netically confined low-pressure arc has been completed with the installation
of a 125 kilowatt d-c generator to supply power to the magnet. The dis-
charge column length is variable up to a maximum of 50 cm, and the maximum
magnetic field is 7000 gauss. Study of the transverse oscillations of the
plasma column, which are due to standing waves similar in character to Alfven
waves, leads to estimates of the density and electron temperature which agree
satisfactorily with information obtained from Langmuir probes and from
relative intensities of spectral lines. The plasma density is between 1013 and
1014 cm-3 and the electron temperature about 5 ev for an 8- A argon dis-
charge in a 1300-gauss magnetic field. Under these conditions the ion temper-
ature is roughly 1 ev.

Delivery of a 1.5-meter grating spectrometer was made and the specified
performance obtained. The instrument was fitted with a punched tape record-
ing system to facilitate use of the computer in obtaining radial intensity
distribution functions by the Abel transformation. Examination of the
departure from Saha equilibrium in the excited state populations of A n,
and an estimate of electron density from Stark broadening of the Balmer
lines of added hydrogen, are under way. The first intensity measurements
show that excited state populations are above Saha (with respect to the elec-
tron continuum) for levels below about 21 ev.

Arrangements were concluded for Professor Susumu Takeda of the Uni-
versity of Nagoya, Japan, to spend a short period in residence to initiate
experiments leading to an estimate of plasma density from the phase shift
of a reflected microwave whose frequency is subcritical. The microwave
equipment has been assembled and tested and is ready for measurements
on the plasma.

Automatic Thermocouple Comparator, A thermocouple compara-
tor has been developed which automatically records data during the com-
parison calibration of platinum versus platinunvrhodium thermocouples.
This device, which places the data on punched tape prior to reduction by a
computer, makes the calibration procedure more rapid and convenient, and
eliminates the errors which may occur during hand recording and transfer
of the data.

Use of the comparator permits automatic recording of the total electro-
motive force developed by the standard thermocouple and the difference
between this emf and that of as many as 11 test thermocouples. The data
can be recorded in several different sequences. One method is to set the
comparator so that a complete set of readings is taken for every 0.5-milli-
volt change in the emf of the standard. Alternatively, readings can be
initiated by clock control at preselected time intervals, or by manual control.

Both the emf of the standard and the difference emf's are converted from
analog to digital form by means of shaft position encoders attached to self-

Automatic thermocouple comparator records data during comparison calibra-
tions. The calibration information comes out on punched paper tape for com-
puter input. Such automation enables the Bureau to provide more rapid cali-
bration service, and permits scientists more time in which to perform the re-
search necessary for more accurate measurements. (See p. 66.)

balancing potentiometer indicators. These digital data are transferred to a
paper tape and, after processing on an automatic typewriter, put on punched
cards. The data are then reduced by a 7090 computer, which fits an equation
to the difference between the test and standard thermocouple emf's, combines
this equation with that used to compute temperatures from the standard's
emf's, and computes the emf developed by the test thermocouple at 1 -degree
(either Celsius or Fahrenheit) intervals.

Thermodynamic Properties of Light-Element Compounds, Under
the sponsorship of the Advanced Research Projects Agency of the Department
of Defense, the Bureau is continuing its comprehensive program of research
on the thermodynamic properties of simple light-element substances which
are important in rocket propulsion. The substances being specially investi-
gated are the two-element and three-element compounds formed by beryllium,
aluminum, and lithium with fluorine, chlorine, oxygen, nitrogen, carbon, and
hydrogen. These substances are important combustion products of rocket
combustion, and some of their properties are therefore being investigated over
a very wide temperature range (0 to 6000 °K) and up to pressures of 100

atmospheres (atm). Nine research groups are engaged in a critical correla-
tion of the available published data and in a systematic experimental program
to measure new values.

An important part of the program is devoted to three types of thermal
measurements on solids — heats of formation, heat capacities at low tempera-
tures, and enthalpies at moderately high temperatures. The combination of
these three properties makes it possible to calculate energies and thermo-
dynamic stabilities of combustion products over wide temperature ranges.
It was found that the most important substances under consideration for which
these three properties had never been measured accurately are four two-
element compounds (BeF2, BeO, Be3N2, and A14C3) and three three-element
compounds (BeAl204, Li2BeF4, and Li3AlF6), and a program of determining
these missing properties is continuing.

The high accuracy of these thermal measurements on three-element com-
pounds has an additional, indirect advantage in practical applications. A
unique opportunity is afforded to test the assumption which is commonly
made that the properties of numerous such compounds of the same type,
which in many cases have never been measured, may be estimated simply as
the sum of those of the simpler compounds from which they were formed.
For example, the heat capacity of BeAl204 was found to be equal, within a
few tenths of one percent, to the sum of those for BeO and A1203 (measured
earlier at the Bureau) for every temperature so far investigated (0 to 900 °C) .

Other groups of the overall program are investigating the vaporization and
gas properties of such substances as those above. One such group used a
newly developed precise high-temperature "transpiration" apparatus to pass
an inert gas over solid aluminum fluoride (A1F3) and measure its vapor
pressure. The heat of vaporization simultaneously found was combined
with the heat of formation of the solid, measured by fluorine calorimetry
earlier in the program, to give an accurate heat of formation of the gas. At
the same time, the results substantiated a recent report that small amounts of
the vapor are in associated form (A12F6) . The apparatus is being 'modified
to study the thermodynamic properties of the hitherto unknown gases A1F2C1
and A1FC12.

The final stage of experimental research of the above types is the critical
correlation of its data with all other data and related properties, to yield an
interconsistent and definitive set of tables of heats of formation and thermo-
dynamic functions. The program is assuming this responsibility for the
compounds of beryllium, aluminum, and lithium, and in so doing is participat-
ing in a permanent, fundamental activity of the Bureau.

Computer Analysis of Low-Temperature Heat-Capacity Data. In
connection with a program to automate low-temperature heat-capacity meas-
urements, computer programs have been developed to analyze the data and
to calculate the thermal functions from the analysis. New data on various
substances are being published at an increasing rate which are either more
accurate than the older data or are on entirely new substances. The heat
capacity is a complicated function of the temperature and no single form of

equation is known that can represent the heat capacity from 0 to 400 °K, the
range of low-temperature heat-capacity data, for all substances with the
accuracy attainable experimentally. A computer program has been developed
to analyze the data using several overlapping equations, the best values in
the region of overlap being selected "manually." To date, the literature data
on over 80 substances have been analyzed and the thermal functions calculated
from the data have been reported. A computer program that requires no
"manual" operation is now being developed.

Thermal Diffusivity Standards. At high temperatures there is an
urgent need for standards of thermal diffusivity and its closely related prop-
erty, thermal conductivity, which is the product of thermal diffusivity and
heat capacity. For poor heat conductors, microcrystalline glasses look
promising in that they are opaque, are electrical insulators, and are available
commercially as reproducible materials. Thermal diffusivity measurements
were made to over 1000 °C on one microcrystalline glass. The measurements
indicated that this material should be adequate as a standard up to 1000 °C,
accurate to within several percent. For higher accuracies two precautions
should be taken: first, the material should be heat-treated near 1000 °C to
become completely reproducible, and second, care should be taken in using
this material near 175 °C where there is a small transition in thermal diffusivity
and some other properties.

Microwave Spectroscopy. A continuing program in microwave spec-
troscopy at the Bureau, partially supported by the Office of Naval Research,
is concerned with measuring the radiofrequency and microwave spectra of
diatomic molecules, with particular emphasis on those molecules that are
known to be present in the interstellar gas. Precise knowledge of their spectra
is necessary before these molecules can be searched for and studied by radio-
astronomical methods. Recently, laboratory measurements were made on
the low-frequency (approximately 100 Mc/s) line spectrum of the molecular
radical SH, generated by the chemical reaction of atomic hydrogen with
hydrogen sulfide gas. Similar chemical techniques are being investigated as
means of producing and studying other radicals of astrophysical interest,
such as CH and SiH.

Nuclear Orientation. Studies made of the photoneutron cross section
in the region of the giant resonance, using an alined holmium target, directly
confirmed the theory that this cross section is associated with the two axes
of the deformed nucleus. This experiment, aside from the importance of
demonstrating this phenomenon, was the first successful experiment using
an oriented nuclear target with an accelerating machine. The work was
performed at the NBS Betatron Laboratory in collaboration with the High
Energy Radiation Laboratory. The alined holmium target was obtained by
cooling a large single crystal of holmium ethyl sulfate to 0.29 °K with the
NBS portable He3 refrigerator.

Shock Wave Reaction Kinetics. Work has been completed on an
experimental investigation of the kinetics of the dissociation reaction N2F4^±
NF2. The experiment involved the combination of shock techniques with

time-resolved absorption spectrophotometry. The experimental data show
that the reaction proceeds by a unimolecular mechanism. The experimental
activation energy was 19 kcal/mole at a total concentration of 6 X 10"2 mole/
liter over the temperature range 343 to 410 °K. (The dissociation energy
is 19.8 kcal/mole.) The Arrhenius frequency factor in the high-pressure
limit was estimated to be 2 X 1015 sec-1. This result indicated that free rota-
tion about the N-N bond probably occurs in the energized activated complex.

An experimental determination of the absorption coefficient for the optical
transition that the difluoroamino radical (NF2) undergoes for light at a
wavelength of 2602 A was determined at temperatures between 438 and
870 °K. The mean result was 535 liters/mole cm.

Thermodynamic Properties of Gases at High Temperatures, A
reasonable approach has been sought for the calculation of thermodynamic

Apparatus used in the determination of the spectra of diatomic molecules
thought to be present in interstellar gas. Precise determination of the line
frequencies is necessary before such molecules can be searched for and studied
by radiotelescopes. (See p. 69. )

properties of ionized gases at high temperatures, in a study sponsored by the
Air Force Special Weapons Center. This includes a treatment thought to be
satisfactory for atoms and atomic ions in circumstances of interest in mag-
netohydrodynamics as well as for more usual equilibrium conditions. In
the past, some approaches have encountered computation difficulties related
to the divergence of the partition function of an isolated atom. The present
practical solution of the problem uses the fact that under the frequently
plausible conditions of Debye screening, the number of states available for
occupancy can be estimated easily in a semiclassical approximation. For a
first approximate calculation scheme, the energies of hydrogenic levels have
been taken as modified by Debye screening according to first-order perturba-
tion theory. The levels are broken off where their available number agrees
with the semiclassical estimate. As the behavior of the screening is different
at different concentrations of ions and, as it also depends on temperature,
there is a joint influence on the partition function and so on the thermo-
dynamic properties. It is only by a careful accounting of the appropriate
derivative relations that the otherwise unknown thermodynamic effects of
these dependences can be taken into account. Programming is in progress
to perform the required operations in a systematic manner via electronic
computer.

A study of the partition function for diatomic molecules at high tempera-
tures has similarly been in progress according to a second virial type
formulation. This has application also to intermolecular interaction effects.

2.1.6. ATOMIC PHYSICS

Atomic physics reserach has continued to be oriented primarily toward the
determination and evaluation of fundamental data relating to atomic prop-
erties and interactions and toward a more basic understanding of the
phenomena involved. The major portion of this work is of primary interest
to the fields of plasma and astrophysics, although the data derived have a
wide area of application in physics, astronomy, chemistry, and engineering.
The Bureau, with partial sponsorship of the Advanced Research Projects
Agency (ARPA) and the National Aeronautics and Space Administration,
continues to be a major international center for research on atomic prop-
erties, and the accumulation and evaluation of the published literature in
its two data centers on atomic energy levels and atomic transition proba-
bilities represent valuable contributions to the scientific community.

In the materials field, properties of semiconductors are under study in a
continuing extensive research program partially sponsored by ARPA. This
research is now being augmented by a study sponsored by the Atomic Energy
Commission of the optical properties of thin films in the vacuum ultraviolet
region.

Continuum States in Rare Gases, New information on the atomic
structures of helium and some of the other rare gas atoms was obtained
in a series of independent experiments which utilized both electron and

714-691 0—64 6 71

Studies of electron interactions in the rare gases have yielded a new and funda-
mental insight into the character of energy states in these gases. The inter-
actions occur in the large cylinder (center). See p. 71.)

photon interactions. These experiments yielded a self-consistent picture
of the higher energy levels in these rare gas atoms, and theoretical studies
gave a new and fundamental insight into the character of energy states in
atomic continua.

Photons produced in the vacuum ultraviolet spectral region by the ac-
celerated electrons in the NBS 180-Mev synchrotron were utilized in studies
of the absorption properties of several of the rare gases. The ultraviolet
radiation obtained from the synchrotron is the only known pure continuum
available in this energy range, and it is well-suited to the study of the
detailed absorption processes in the far ultraviolet.

A series of absorption features were observed in helium gas, at energies
some 35 volts above the energy necessary to ionize the neutral helium atom.
At these energies, two competing processes can take place: the ultraviolet
photon can either remove one of the electrons completely from the atom,
or can leave the atom in a short-lived neutral state by elevating both its
electrons to higher excited states. Since these two processes are strongly
mixed, the observed spectrum exhibits the anomalous features characteristic
of autoionized states.

Theoretical studies of the absorption characteristics of helium showed
excellent agreement with the observations, and have led to a greatly im-
proved understanding of atomic energy states that are mixtures of discrete
and continuum states. New calculations for a series of autoionizing levels
in helium indicated that relatively crude calculations can be expected to

predict level widths within a factor of two or three of experimentally deter-
mined values.

These same atomic states in helium were also studied through obser-
vations on the energy losses suffered by nearly monoenergetic electrons
passing through helium gas. These measurements were performed with new
apparatus designed to measure electron-scattering cross sections in the
range from 500 to 5000 electron volts. This apparatus will be used to
make further accurate and detailed studies of electron-scattering cross sections
for various atoms as functions of both angle and energy.

Characteristics of energy losses of electrons scattered by helium were
in complete agreement with results of the experiments performed with the
ultraviolet photons from the synchrotron.

A new and extremely monoenergetic electron gun and an analyzer were
constructed and utilized in studies of the absorption characteristics of rare
gases. Experiments performed with this apparatus in helium gave evidence
of an anomalous transparency to low energy electrons. The observed
"window" in the helium gas was extremely narrow, and lay well below the
energy of the first excited state.

In addition to those of helium, the absorption characteristics of neon
and argon were studied in both the photon and electron experiments. In
each case, results qualitatively similar to those described for helium were
observed. Numerous autoionizing states were identified, and in neon
two resonances below the first excited state were observed. No such low-
lying states were seen in argon, however.

These studies are expected to yield data on the generalized oscillator
strengths in the continuum and to lead to an understanding of these states.
The results will be of fundamental interest to both astrophysicists and plasma
physicists, and are necessary to the interpretation of astrophysical and
thermonuclear phenomena.

LIMIT= I89.6&

Absorption spectrum of helium obtained using the NBS synchrotron as a source
of light. The ultraviolet radiation from the synchrotron is the only known
pure continuum available in this energy range. (See p. 71.)

Plasma and Astrophysics, The Bureau continues to be the world cen-
ter for the collection and determination of much of the atomic data needed
by atomic physicists and particularly by plasma and astrophysicists. Such
data are important to the proper diagnostics and understanding of processes
occurring in hot gases. Work in this field was supported by ARPA and the
Bureau.

In addition to the work mentioned in the previous section on continuum
oscillator strengths, work on the determination of the discrete oscillator
strengths (or transition probabilities) in atoms continued.

Research continued on use of the wall-stabilized arc for the measurement
of transition probabilities. The shifts and widths of several oxygen lines
were measured, and the results are in good agreement with recent theories
on line broadening in dense plasmas. This method represents a new and
simple way of analyzing dense plasmas of heavy elements, and should lead
to a better understanding of high-temperature plasma phenomena.

The cross section for elastic scattering of the slow, 1-ev electrons by
hydrogen atoms was measured by the electrical conductivity method. In
contrast with earlier experimental measurements by research groups else-
where, the result agrees well with recent theoretical values and confirms
the general consistency of the spectroscopic analysis of the hydrogen plasma.

The relative transition probabilities for a number of lines of singly and
doubly ionized oxygen were determined utilizing a magnetically driven shock-
tube. The results agree very satisfactorily with the theoretically obtained
values. No attempt was made to present absolute values, as attainment
of complete local thermodynamic equilibrium was somewhat uncertain.

Modified Hartree-Fock calculations of transition probabilities were com-
pleted for the major transitions in two- and three-electron atoms and ions.
Relative transition probabilities were calculated with the Racah methods
for the spectrum of doubly ionized vanadium.

Atomic Energy Levels. Emphasis continued to be centered on the
observation and analysis of the rare-earth spectra. Extensive laboratory ob-
servations, including the strong absorption lines and Zeeman patterns, were
carefully scrutinized to determine the ground state and over 100 "even"
levels for Ce I. The spectrum of Ce m was observed with a sliding spark, and
measured from 700 to 1100 angstroms (A). Some 2000 lines are known,
of which 75 percent are now classified. The strongest line of Ce III, A3055.589
A, may possibly be present in the solar spectrum, where an otherwise uniden-
tified faint line has been observed at A3055.594 A. If this identification is
correct, it provides the only evidence of a third spectrum among the solar
lines A > 3000 A.

Measurements and calculations of the Zeeman patterns of 1307 lines in
the first three spectra of ytterbium were compiled preparatory to a new de-
scription of these spectra comprising more than 6500 lines. Measurements
of approximately 10,000 lines of Tm I, Tm II, and Tm in were made, covering
the interval 2300 to 11000 A.

A new edition of the extensive solar spectrum table is near completion.

Highly accurate measurements were made of lines in the spectra of Krypton 86
and Mercury 198 for use as secondary wavelength standards. The orange-red
line in the spectrum of Kr8e has been the International Standard of length for
more than three years. (See p. 75.)

A theoretical study on the nonlinear effects in the spectra of elements in the
iron group contributed significantly to the understanding of the electronic
configurations in these atoms.

Wavelength Standards. The program on mercury atomic beams and
Zeeman filters, undertaken in connection with the redefinition of the meter,
concluded with experiments comparing the wavelength of the 2537 A line as
obtained from these two sources. Highly accurate wavelength measurements
of additional mercury and krypton lines suitable for standards were also
completed.

Infrared Spectroscopy of Gases. The infrared absorption of a band
of carbon suboxide (C302) was measured under high resolution. Analysis
of the spectrum provided the first unambiguous evidence that this molecule
is linear and must have an unexpectedly low bending frequency. A parallel
band of ethane-1-C13 was also analyzed. The results are in agreement with
C — C bond length measurements obtained for propane.

A forbidden vibronic band of NO that was predicted to have a transition
probability produced by the interaction of the two electronic states was ob-
served. Both frequency and intensity measurements were made. Within
experimental error, the intensity of the band was found to be the same as that
predicted theoretically.

Measurements and a partial analysis of 15 absorption bands of CH3D
were completed as part of an AEC-sponsored program of measurements of
deuterated compounds. Under the same sponsorship, measurements and
analysis of a number of bands of DCN were completed. This work com-
plements a recently finished analysis of the spectrum of HCN. In addition
to furnishing values of potential constants and rotational constants for two
isotopic species, the work on HCN and DCN emphasized the importance
of including certain higher-order constants in the analysis so as to achieve
satisfactory agreement between the observed and calculated spectra. Such
higher-order terms were previously unnecessary, but the advent of higher
resolution and more accurate measurements has necessitated use of more
exact expressions for the energy levels.

Shapes of Rotational Lines as Influenced by Pressure, Measure-
ments were made on the pressure broadening of infrared absorption lines
for the gases HO, DC1, CO, and HCN. In addition to some self -broadening
measurements, broadening by various types of foreign gases was investigated.
The broadening has been demonstrated to be nearly independent of the
vibrational level involved, although it does depend on the rotational level.
The most significant work involves the measurement of the broadening of
HCN lines due to the pressure of HC1. These two molecules have a large
dipole moment and thus strongly interact when they approach each other.
This work was supported by the Cambridge Air Force Research Center and
the AEC in addition to the Bureau.

Absorption Spectra of Solids. The infrared spectra of several very
interesting solids were completed or are now under study. Infrared studies
of the compound 4CsCI • 3HC1 • 3H20 and its deuterated counterpart were used
to show that, contrary to previous expectations, they do not contain the
HC12" ion but only the ions Cs+, CI", and H30+. Work is in progress to
determine if the elusive HCL" ion is present in certain pyridine salts.

Spectra of polyhalide compounds were also analyzed. These compounds
are similar to the recently discovered rare gas compounds (i.e., XeF2) and
are of great interest. The Bureau is uniquely suited for studies of polyhalide
compounds because of the availability of spectrometers which can be used
in the far infrared region where these spectra are found.

Solid State Physics. The research program in solid state physics.
which is partly supported by the AEC and the ARPA, concentrates on four
major interdependent areas: electronic transport, optical characteristics,
magnetic resonance, and dielectric properties. This experimental program
is supported by theoretical studies and by crystal growth and structure investi-
gations. The main emphasis is on a group of semi-insulators and semi-
conductors (namely, the Ti-0 compounds: Ti-oxides and titanates) which
have important uses in many different fields (such as dielectrics, masers,
phototropic materials, etc. ) . Other substances under investigation are spinel,
CdTe, PbF2, and several azides.

A study was made of the electron spin resonance spectrum of molvbdenum
in rutile. Fine structure, hyperfine structure, and superhyperfine structure

were observed and interpreted. Use of circularly polarized microwave
radiation enabled the unambiguous determination of the sign of the g-factor.

Measurements of the Seebeck coefficients of Ti02 and SrTi03 down to 15 °K
have shown that the phonon-drag effect contributes most to the value of the
coefficient of rutile at low temperatures, while it seems to be absent in SrTi03.

Electronic energy band calculations for Ti02 indicated that the conduction
and valence band of this material are mixtures of Ti-Sd and 0-2/? orbitals.
The binding is not completely heteropolar in nature. Qualitative agreement
with many characteristics of the substance can be obtained (energy band gap,
width of valence band, higher conduction bands, etc.) . A similar calculation
for cubic titanates (perovskites) is in progress.

The optical spectrum of Co in a Mg-Al-spinel crystal can be interpreted in
terms of calculated level schemes (crystal field theory). The measurements
confirm that Co prefers the tetrahedral site rather than the octahedral one.

The nitrogen nucleus in azides (NaN3, KN3, HN3) is being investigated by
means of nuclear magnetic resonance and quadrupole resonance techniques.
The quadrupole coupling constants of each of the three N nuclei in HN3 were
determined from the microwave spectrum.

Good crystals of CdTe were produced using the Bridgman method; the
photoelectric properties of this substance are being explored.

Electron Optics. A problem which has plagued electron physicists for
years is the production of well-collimated electron beams of low energy.
Such a beam is a basic requirement in almost every experiment in electron
physics and in many in atomic physics. A new and somewhat novel analysis
of the physics involved in the production of such beams has given rise to the
development of a series of electron guns of precise design. These guns, which
perform much better than previous designs, were utilized in the previously
described study of energy losses in rare gases.

Measuring Velocity of Light. A multifaceted program was instigated
to remeasure the velocity of light to at least one more significant figure. The
method involves the measurement of beat frequencies between two optical
lines emitted from a helium-neon laser. A comprehensive study to determine
the feasibility of detecting and measuring beat frequencies of the order of
1012 cycles per second between two optical lines in the helium-neon laser was
successfully completed. An experimental investigation was initiated by
Egerton, Germeshausen & Grier, Inc., under contract to the Bureau to de-
termine the necessary design considerations involved in the construction of
a modified cathode-ray tube for the beat frequency measurement.

Two helium-neon lasers have been constructed to investigate the various
methods of stabilization of the laser lines. These lasers are also being used
to investigate the various lines available for and most suitable for the beat
frequency detection.

Optical Pumping. For the past year, work progressed on an experi-
ment to pump xenon 129 optically at 1469 A. A strong resonance lamp was
designed and constructed to give a radiation flux of approximately 1015
photons/sec per steradian at 1469 A with no appreciative self-absorption.

The radiation is emitted through a sapphire window fused to the lamp.
Experiments are now in progress to detect the optically pumped signal in
xenon 129.

Magnetic Moment of the Proton. An experiment was undertaken to
determine the magnetic moment of the proton in units of the nuclear magne-
ton. It is hoped that this determination will lead to the resolution of a
50 ppm discrepancy in this constant reported by various investigators.

Experimental Atomic Collisions. A new instrument for the study
of photodetachment of negative ions is being completed. This instrument
will provide significantly greater resolution of both the ion beam and the
photon beam. Studies of the behavior of the cross sections near threshold
'for photodetachment of atomic ions will be undertaken without the assistance
of prior theoretical assumptions.

2.1.7. RADIATION PHYSICS

The radiation research program of the Bureau is directed toward meeting
technical needs in three general areas: radiology, nuclear science and tech-
nology, and radiation processing. For example, medical radiologists are
requesting improved accuracy in the determination of source output and
absorbed dose. Since the calibration of clinical instruments is usually two
steps removed from the national standard, and since the transfer instruments
presently available have rather low precision (maximum effect of random
errors being of the order of 1 percent) , it is desirable to increase the accuracy
of the national standards. The NBS transfer instrument that is now used
for national and international comparison has an accuracy of 0.2 percent,
and extensive research efforts continue in this area.

Demands from research workers for more accurate cross sections and for
more information about the nature of the interaction between radiation and
materials have resulted in an expanded program in these areas. In addition,
research laboratories require radioactivity standards accurate to within 1 per-
cent; such accuracy is difficult to attain but is being provided with special
effort.

Increased applications of radiation in industry for such purposes as preser-
vation of foods, crosslinking of polymers, sterilization of sutures, and activa-
tion analysis have created a need for improved standards and dosimetry at
high radiation energies and at high dose levels. Industrial applications re-
quire measurements somewhat less accurate than those required for medical
or nuclear research applications, but beams whose intensity is usually of the
order of kilowatts of radiation power create severe measurement problems.

Considerable effort is currently being applied to the design and construction
of equipment which will be used to implement an enlarged research program
in the new laboratory facility at Gaithersburg, Md. Sources with higher
intensity, such as the NBS 100-Mev linear accelerator (Linac) and the 1.5-
and 4-Mev direct accelerators which will become operational in 1964, will
make it possible for the Bureau to meet the increased demands for basic
experimental data, improved standards, and refined measurement techniques.

X-Ray and Gamma-Ray Dosimetry

Cavity Chambers. Instruments used as laboratory standards for X- and
gamma-ray measurements by medical institutions, research laboratories,
manufacturers, atomic energy installations, the Military, and Civil Defense,
are calibrated by comparison with the Bureau's standard instruments. The
accuracy requirements for these calibrations have been steadily increasing.
Close agreement between NBS standards and those of other countries is also
important. Accordingly, improvements have been made in the Bureau's
X-ray free-air-chamber standards, in the calibration accuracy of gamma-ray
beams, and in diaphragm sytsems for evaluating stem corrections in certain
types of radiation instruments.

Photographic Dosimetry. Work continued on extending photographic
dosimetry to exposures of 1 milliroentgen (raR) or less of high-energy X- and
gamma-radiation. Post-exposures to 620-millimicron infrared radiation,
chemical treatment of the films, and special development techniques extended
the range downward by close to a factor of ten. Microphotographs showed
that this extension is achieved by an increase in grain developability (larger
number of grains developed at any given exposure), an increase in the
projected area of the grains, and a general change in grain shape.

Further experiments were performed on films that had been exposed to
two widely different rates of gamma radiation and, after development in a
surface developer, had shown marked reversal and re-reversal effects. Most
of the work on these films during the past year was done at the Armed Forces
Institute of Pathology (Biophysics Branch). The measured quantities, i.e.,
developed silver per unit density (the photometric equivalent), mass of de-
veloped silver per grain, and density per grain (proportional to the densito-
metrically effective projected grain area), were studied for both intensities
as a function of exposure. Anomalous behavior was found for the number
of grains in the ascending branch of the density-versus-exposure curve ob-
tained with high intensities, and for the photometric equivalent at the re-
reversals for the very highest exposures both with high- and low-intensity
radiation. Conclusions were drawn from these findings concerning the cause
for the rate dependence of the maximum density attainable, and for re-reversal.

A review paper on the use of photographic film for personnel dosimetry
was presented at the Symposium on Personnel Dosimetry Techniques for
External Radiation, held in Madrid under the sponsorship of the European
Nuclear Energy Agency.

Solid State Dosimetry. The investigation of the response to X-rays of
silicon radiation detector cells of the diffused p-n junction type, when op-
erated as photodiodes and photovoltaic cells, was continued. Different cells
of the same type were investigated and methods of measurements were im-
proved in order to provide increased accuracy. The temperature depend-
ence of the photocurrent produced by X-rays was measured between 25 and
50 °C and found to be similar to that observed for photocurrents produced
in silicon photocells by visible light. Measurements of the energy depend-
ence of the generated photocurrent were extended to moderately and lightly

filtered X-rays of half -value layers between approximately 0.07 mm and 16.0
mm aluminum. Preparations have been made for comparative measurements
of the response to X-rays of silicon radiation detectors of different types.

Response of Silicon Charged Particle Detectors at Low Tempera-
tures, A program to investigate and develop solid state counters for nu-
clear physics experiments is under way. Recent measurements were carried
out to investigate a suggestion that Li-drift detectors should function as well
near absolute zero as at elevated temperatures. The results of two dissimilar
experiments, designed to eliminate contact anomalies at low temperatures,
indicate that the response exhibits a sharp decrease at a temperature of about
30 °K. Subsequent measurements with a silicon surface barrier detector
of 3000 ohm-cm resistivity show that the anomalous region for this relatively
undoped silicon extends from about 17 to 25°K. Corroborative experiments
and experiments to confirm recent theories as to the physical origin of the
effect are in preparation. Beyond the interesting solid state physics implied
by this work, an appropriately doped silicon detector and beta-emitter with
a simple charge-sensitive preamplifier and integral discriminator may have
possibilities as a very accurate and convenient secondary temperature
standard.

Radioactive Sources

Scattered Spectrum of Water-Shielded Sources. Measurements have
been made to determine the gamma-ray spectra produced by the Bureau's
two water-shielded cobalt 60 radiation sources. A demountable model was
constructed having separate radioactive parts in the form of thin wires. A
series of ion chamber measurements made with the model in different stages
of assembly gave the scattered intensity contributed by the various com-
ponent parts and by the water. The scattered intensity was found to be 21
percent of the total, and the spectral distribution approximately the same as
that of singly scattered primary photons. This information, permitting
more accurate estimates of absorbed dose delivered by these sources, will
make feasible an experimental comparison of calorimetric and ionization
methods of radiation dosimetry.

Standards of Radioactivity. In the past year the sum of standards
sold and calibrations performed exceeded 600; several international cam-
parisons have been carried out; at least two new methods of measurement
have been developed; and a material contribution has been made to the
development of the radiation standards laboratory of the Bureau Inter-
national des Poids et Mesures by sending a staff member to work at Sevres
for six months. An iodine 125 solution standard and a cerium 139 gamma-
ray point-source standard have been developed and a new series of krypton
85 standards has been issued. Intensive investigation of the accuracy of
mass-spectrometric analyses of carbon 14 in carbon dioxide, carried out in
conjunction with the Applied Analytical Research Laboratory, resulted in the
NBS value of the half life of carbon 14 being reduced 15 years to 5745 ±50
years, a change which is less than one-third of the estimated probable error.
This determination brings the NBS value into close agreement with the

Cambridge average of British, Swedish, and United States results, adopted
in July 1962, of 5730 ±40 years.

The two new methods of measurement which are of note are (1) the use
of silicon at temperatures below 4.2 °K for the detection of beta particles,
and (2) the use of Auger electrons to indicate the source self -absorption
for X-rays in the preparation of standards of the electron-capturing nuclide
iron 55.

The low-level radioactivity program has made considerable progress,
and intercomparative measurements have been satisfactorily carried out on
samples of strontium-yttrium 90 and iodine 131 in water distributed by
the U.S. Public Health Service, and of iodine 131 in evaporated milk
distributed by the U.N. International Atomic Energy Agency. A new
method has been developed for the quantitative analysis of low levels of
uranium in water and in urine by ion exchange without lengthy preparation,
thereby reducing the time required for a measurement from four to two
days.

Model used to determine the gamma-ray spectra of the Bureau's two water-
shielded cobalt-60 radiation sources. Pencils with tapered ends contain radio-
active material; flat-ended pencils are solid dummies. Cavity ionization cham-
ber in center of model measures intensity of radiation. (See p. 80.)

Radiation Interaction With Matter, Investigations have been made
of some of the important processes involved in the interaction of electrons
with matter in the energy region from 50 to 500 kev. These processes
include electron single scattering with and without atomic excitation. The
experimental studies were carried out with the NBS 500-kev electron ac-
celerator and with magnetic and scintillation spectrometers. The experi-
mental results show good agreement with available theoretical predictions
for the process of scattering without atomic excitation. However, for the
process of scattering with atomic excitation, there are large discrepancies
between experiment and theory which are attributed to the approximations
used in the available theory.

Radiation Interaction with Nuclei

The Interaction of Bremsstrahlung with Alined Nuclei. During the
last five years, a series of experiments has been carried out to study the
interaction of high-energy photons with nuclei known to have large intrinsic
deformations (i.e., nuclei with large intrinsic quadruple moments) . Studies
were made of both the scattering and the absorption of photons by these
nuclei. The analysis of these data indicated such nuclei probably have a
large intrinsic tensor polarizability. During the last year and one-half,
this part of the polarizability of the holmium nucleus has been studied directly
in an experiment designed to show that the nuclear absorption cross section
in the giant resonance energy region depends upon the orientation of the
nucleus with respect to the photon beam. The experiment has been carried
out in collaboration with a group from the Low Temperature Laboratory-
Holmium nuclei are alined along the oaxis of a single crystal of holmium ethyl
sulfate by the Bleaney method. The crystal, cooled to 0.03 °K by means of a
continuously operating He3 refrigerator, can be rotated with respect to the
beam from the betatron.

The experiment consists of measuring the yield of photoneutrons from
the holmium ethyl sulfate crystal as a function of the orientation of the
crystal's c-axis with respect to the photon beam. This is done at a series
of six betatron operating energies between 10 and 20 Mev. At temperatures
above 4.2 °K, only slight asymmetries are observed in the yield of photo-
neutrons as the crystal is rotated. To a large extent these can be accounted
for by the slight geometrical asymmetry of the crystal. At 0.3 °K, consid-
erably larger asymmetries are observed that can be attributed to the tensor
polarizability of the holmium nucleus.

Nuclear Matter Distributions as Determined from Neutral Meson Photo-
production. The major process contributing to neutural meson photopro-
duction near threshold leaves the residual nucleus in its ground state. Thus,
the process is completely coherent and exhibits strong nuclear size effects.
In the Born approximation, these nuclear size effects can be represented by
a form factor. The form factor for tt° photoproduction is the same as that
for elastic electron scattering, neglecting nucleon size, except that the electron
scattering experiments observe the distribution of electric charge in the
nucleus, whereas the tt° photoproduction observes both protons and neutrons

Holmium ethyl sulfate crystal used to measure the dependence of the yield of
photoneutrons from holmium on the orientation of the nucleus with respect
to the photon beam direction. Nuclei were alined by cooling the crystal to
0.29 °K. (See p. 82.)

with equal weight and is thus a measure of the nucleon matter distribution.

By comparing the results of electron scattering and ir° experiments, it may
be possible to determine information about the relative distributions of
protons and neutrons in the nucleus.

During the last several years, a series of measurements has been made of
the photoproduction of tt° mesons from complex nuclei. The results of
measurements on elements carbon, aluminum, copper, cadmium, and lead
have indicated nuclear rms radii agreeing within the errors with those de-
duced from electron scattering experiments. The rms radii are determined
to within 2 X 10"14 cm.

A series of measurements are currently in progress to study tt° photopro-
duction from the elements carbon, magnesium, aluminum, silicon, and sulfur
to improve the absolute accuracy of the measurements and to compare the
radii of neighboring nuclei. In addition, aluminum with a spin of 5/2
should be a very good element with which to investigate the possibility of
spin-dependent contributions to the 7r° photoproduction. Preliminary anal-
ysis of data indicates that the elastic photoproduction process does not seem
to be dependent on the spin of the target nucleus. The data for aluminum
are not different (except for size effects) from the data obtained from mag-
nesium and sulfur, both of which have a major isotopic abundance of spin
zero. A rough fitting of the data from magnesium, aluminum, and sulfur
indicates that the ratio of the nuclear matter distribution to the electric
charge distribution is constant to within the probable error of 2 percent.

An attempt is being made to obtain a sample of 018 water to make similar
measurements. This should be an especially interesting case since 018 con-

sists of a closed O16 shell with two e?-wave neutrons outside the closed shell.
Neutron Time-oj -Flight Technique. Measurements of the interaction
of high-energy neutrons with nuclei are useful both for investigation of the
parameters of nuclear models and for calculation of the shielding character-
istics of bulk matter. An experiment has been performed to measure the
elastic and inelastic scattering cross sections, as a function of scattering
angle, of 14-Mev neutrons on calcium. The experimental technique utilizes
measurement of the flight times of the scattered neutrons to determine their
energies; groups of neutrons having flight time differences as small as
1.5 X 10~9 sec have been resolved. Theoretical calculations of the elastic
cross sections have also been carried out, using the optical model of the
nucleus, for a wide range of neutron energies. The experimental results
for calcium agree with the general predictions of the theory, but have also
confirmed small discrepancies previously reported.

The target area for measurement of the scattering of 14-Mev neutrons. The
neutrons are produced on a target at the center of the thin-walled sphere. The
counter at left center records the time at which a neutron leaves the target, and
the counter at the right rear detects this neutron after it has scattered from the
small cylindrical scatterer in the right foreground. (See p. 84.)

Previous Bureau investigations using y-rays have demonstrated the large
deformation of the holmium nucleus. The neutron time-of-flight equipment
that has been developed will permit further investigation of this deformation
using 14-Mev neutron scattering from alined holmium nuclei.

Particle Interaction Theory. More than 30 elementary particles and
resonances have been found. The classification and correlation of the prop-
erties of these particles — masses, spins, parities, moments, and decay widths —
are among the most challenging problems of modern physics. Interestingly
enough, the methodology used in attacking this problem of elementary par-
ticle spectroscopy is quite analogous to the now familiar techniques of nuclear
and optical spectroscopy.

The introduction of unitary symmetry (SU3) in the octet model or "eight-
fold way" to describe the strong interactions between elementary particles
has recently been proposed and its consequences are now being explored.
Unitary symmetry is a generalization of isospin symmetry which also in-
cludes the strangeness quantum number. In the octet model, the spin^^
baryon, i.e., the neutron, proton, S~, 5°, S+, E~, E°, and A particles are
considered as members of a unitary multiplet just as the neutron and proton
are the two members of an isospin multiplet. Similarly, the pseudoscalar
mesons, K°, K+, ir~, 7r°, 7r+, 77, K~, K° are also members of a unitary multiplet.

Particular attention has been paid to the formulation of possible tests of
the theory by examining reactions of the type

meson + baryon— »baryon resonance + meson

and
meson + baryon— »baryon resonance + vector meson.

The role of the gamma-ray in the eightfold way has also been investigated
in detail. Quantitative predictions about processes like the photoproduction
of baryon resonances and their electromagnetic decays have been formulated.
Preparations for New Linear Accelerator. Progress continues in
the design and construction of the NBS linear accelerator (Linac). Tests
of the first prototype accelerator section are complete and have been valuable
in fixing the final production phases of the new machine. Completion of
the accelerator is expected in the fall of 1963 and installation in the new
laboratory at Gaithersburg, Md., in the spring of 1964. Research with the
accelerator will meet the increasing need for basic data and physical measure-
ment technique developments in the use of intense high-energy electron
beams in radiography, radiology, nuclear physics research, and radiation
processing of materials.

Linear Accelerator Theory. Existing theories of linear accelerator per-
formance have always assumed that the Linac waveguide is a broadband
device without dispersive properties. In reality the Linac waveguide is highly
dispersive and has a passband only a few megacycles wide. Substantial
fluctuations in th rf power transmitted by the waveguide of the prototype of

the NBS accelerator have led to the development of Linac theory to include
these dispersive effects, and theoretical calculations successfully predict the
observed fluctuations. The theory has been extended to include dispersive
effects in the heavily beam-loaded Linac, and a number of new predictions
have been made concerning Linac behavior. These predictions are of con-
siderable importance to many linear accelerators being considered at the
present time. Similar calculations have been made of waveguides being
considered for the very large linear accelerator being constructed at Stanford
University. When the NBS linear accelerator is available, an attempt will
be made to confirm other interesting predictions of these calculations.

Heavy-Ion Source for Magnet-Optic Studies. A 400-kev krypton ion
source has been developed to study the detailed performance of beam de-
flecting magnets and of magnetic spectrometers. Since a 400-kev krypton
ion has the same momentum as a 250-Mev electron, this will allow detailed
study of magnets over the range of interest on the NBS Linac.

The present performance of the ion source is sufficient for detailed study
and ray tracing of individual magnets. Further refinements will be necessary
before it can be used to test entire magnet systems where the total flight path
in the system approaches 150 feet.

The first bending magnet of the NBS beam-handling system has been
delivered and measurements of the deflecting properties of this magnet are
being made.

High-Current Beam-Handling Problems. The very high beam current
of the NBS Linac poses unique and severe problems of metal fatigue and heat
dissipation in collimating and stopping the beam. A number of measurements
have been made in collaboration with High Voltage Engineering Corporation
and Yale University on these problems, using the Yale Linac. The results of
these measurements have demonstrated the extreme importance of the pulsed
nature of the Linac beam on metal fatigue and on cooling behavior and have
led to design information which will be used in developing the NBS beam-
handling system.

Equipment for Use With Linac. The current effort in the Linac research
program is to develop major long-lead-time pieces of experimental equipment.
It is hoped to have this equipment developed and on hand at the time the
Linac is available. The major items being developed are (1) a magnetic
spectrometer for performing elastic and inelastic electron-scattering experi-
ments, (2) a magnetic spectrometer for detecting heavy charged particles,
protons, deuterons, alphas, etc., (3) equipment for producing beams of
positrons and monoenergetic photons, (4) facilities and equipment for study-
ing (y, n) reactions using nanosecond time-of -flight techniques, and (5)
equipment and techniques for accurate and convenient electron beam
monitoring.

Data-Logging and Data-Handling System for the Linear Accelerator.
A detailed examination has been made of the needs for data-logging and
data-processing equipment for the experimental programs using the linear
accelerator. This survey has indicated that there are major scientific, tech-

nical, and economic advantages to the use of a small on-line, general-purpose
computer for these datalogging problems.

As there exist satisfactory commercial computers for these applications,
the major problems are the development of various types of input and display
equipment and program organization of the computer.

An examination of the experiments which would use this system reveals
that a complete data-logging program can be accomplished by the use of one
or more of a small number of basic building-block input subsystems. The
logical design of these subsystems and detailed circuit drawings are nearly
completed. Hardware to construct a portion of the input system is ordered
and construction began in July 1963.

The computer chosen for this system, SD-920, is on order and delivery
is expected in September 1963.

Considerable effort is now going into an investigation of the coding and
programming problems which will occur with simultaneous usage of this
system by several experimental groups and in procedures for rapid and
convenient program control to meet the variable and uncertain needs of
experiments. While these are not easy problems satisfactory solutions seem
to be feasible.

It is hoped that this data-logging system will be in useful operation on
experiments in approximately one year.

2.1.8. LABORATORY ASTROPHYSICS

The Joint Institute for Laboratory Astrophysics (JILA), established in
April 1962 on the University campus at Boulder, Colo., is a collaborative
effort of the Bureau and the University of Colorado. The Institute provides
a center for both research and advanced training in areas of physics and
astrophysics which provide the scientific basis for meaningful measurement
in very hot gases. Here, scholars in many specialties are given the oppor-
tunity to exchange ideas and data. The staff is composed of appointees
of both the Bureau and the University of Colorado.

Astrophysics is the application of physics to problems of astronomy. At
JILA, theoretical rather than experimental work is emphasized, with greatest
effort concentrated in those areas of theoretical astrophysics which provide
the physical understanding for fundamental processes in stellar atmospheres.
This effort is closely related to low-energy physics.

In atomic physics, heaviest emphasis was placed on atomic, electronic,
and ionic collision processes. Also studied were optical resonance phenomena
and lasers, ultraviolet and visible atomic spectroscopy, and continuous ab-
sorption coefficients of ions, and ionic mobilities.

In astrophysics, data from the 1962 solar eclipse were analysed, and work
on solar flares was continued. Theoretical techniques to describe departures
from local thermodynamic equilibrium of a gaseous atmosphere are under
development. Attempts are underway to determine helium abundance in the
solar chromosphere and the chromospheric structure of certain types of stars.

714-691 0—64 7 87

Physics of Atomic Collisions, The mobilities and diffusion coeffi-
cients of three species of helium ion were measured with high precision,
and the rate coefficient for the formation of helium molecular ions in three-
body collisions was also determined. This work is particularly interesting
because it appears to conflict with conventional theoretical limits on the
molecular helium mobility. Similar measurements were made in neon. Ex-
periments being planned include photodetachment of negative ions of molec-
ular oxygen under conditions of thermal equilibrium at room temperature.
With AEC support, a detailed experimental study of dissociative ionization
of hydrogen molecules by electron impact was completed. Specifically, the
kinetic energy distribution of protons from the dissociating ions was
measured and — for the first time — agreement obtained with theoretical pre-
diction. More importantly, the angular distribution of the protons was de-
termined with respect to the ionizing electron beam direction, and this dis-
tribution was shown to be highly anisotropic, as predicted. This result
proves that most of the values of cross sections for collisions of dissociating
molecules reported in the literature should not be considered correct, since
the geometries of these experiments usually were predicted on the assumption
of isotropy. Studies on angular distributions in oxygen and nitrogen are
continuing.

The photodissoeiation of the positive ion of molecular hydrogen is being
studied in a cross-beam experiment also supported by AEC. The integrated
cross section appears, in general, consistent with theoretical expectation, al-
though the spectral distribution of the cross section may be anomalous.

An experimental study of the elastic scattering of monoenergetic electrons
from atomic hydrogen in crossed beams is in progress-
Analysis of data taken earlier on the photodetachment cross section
of the negative iodine ion was completed with financial support from ARPA-
ONR and in collaboration with the Atomic Physics Division with the result
that the binding energy of this ion is now known to an accuracy of 3 mv.
In addition, comparison with shock-tube data of other experiments provides
insight into the unusually small depression of negative-ion binding energies
in dense plasmas. Concurrently, theory for the threshold behavior of nega-
tive ion photodetachment, including the effects of polarization, is being
developed by one of the JILA Visiting Scientists with a stipend from the
University of Colorado's NSF Grant. The experiments on the negative
iodine ion will provide a critical test of the theory when the effects of the
iodine quadruple moment have been included in the theory.

The most accurate cross-section calculation for the negative hydrogen
ion bound-free absorption coefficient yet determined theoretically was com-
pleted, and it is in excellent agreement (within a few percent) with the
results of precise experiments. Meanwhile the Bureau is assisted in this
effort by a CU contract from AF Special Weapons Center involving de-
tailed calculations of the free- free absorption coefficient which are being
made using these accurate wave functions. A new calculation of the cross
section for ionization of the negative hydrogen ion by electron impact shows

that the previous result was too large. An attempt to measure this cross sec-
tion is planned.

Also in progress by JILA Visiting Scientists are a calculation of the cross
section for ionization of atomic hydrogen by proton impact and a study of
the ionization of Fe xiv by electron impact.

This two-quantum photodetachment probability for negative iodine and
other ions was calculated. A giant-pulse ruby laser makes possible an
experimental measurement of this probability using the photodetachment
apparatus.

Astrophysics. Work continued on the development of theoretical tech-
niques for describing a gaseous atmosphere, departing from local thermo-
dynamic equilibrium, in which aerodynamic phenomena provide an energy
source but are too small to provide a momentum source. An attempt was
made to extend this work to treat the solar corona and the rocket ultraviolet
spectrum of the sun.

The chromospheric spectra from the very successful 1962 Solar Eclipse
Expedition to New Guinea were analyzed in collaboration with astro-
physicists from the High Altitude Observatory at Boulder, Colo., and the
Sacramento Peak Observatory at Sunspot, N. Mex. A serious discrepancy
in the literature concerning the temperature of solar prominences has been
explained.

Two other investigations are nearly complete: a study of the excitation
of helium lines in the solar chromosphere leading to a determination of the
helium abundance, and a study of proton kinetic energy distributions in
coronal-loop solar prominences.

A set of observations of line profiles of the calcium H and K lines in
spectra of G, K, and M-type stars were completed at Mt. Wilson Observatory
near Pasadena, Calif., in collaboration with the UCLA Department of
Astronomy. These data will be interpreted in an attempt to discern the
chromospheric structure of such stars.

Work on solar flares was continued by a JILA Visiting Scientist (NSF).
An analysis of the spectrum of the September 2, 1960 flare was completed,
and some of the 1962 eclipse data were reduced.

An unusual photoelectric instrument was developed for measuring the
relative strength of solar chromospheric continua on both sides of the
Balmer discontinuity. The equipment was used in Alaska during the July 20,
1963 solar eclipse.

Resonance Physics. The possibility that optical pumping by sunlight
occurs naturally in the sodium of the earth's upper atmosphere was inves-
tigated with the result that the effect appears negligible except in the case
of artificial sodium releases from rockets at higher altitudes. A theoretical
investigation was made of hydrogen atom spin exchange collisions, with
applications to the operation of a hydrogen maser. Optical pumping of
rubidium vapor in the presence of a high-pressure buffer gas was observed
experimentally using natural sunlight.

A giant-pulse ruby laser, producing about 1 joule and up to 50 Mw of
monochromatic light, was developed for the purpose of studying nonlinear
interactions of atoms and matter with radiation. The feasibility of meas-
uring the two-quantum photodetachment of negative iodine ions has been
studied. A fluorescence experiment on anthracene has been carried out in
collaboration with the Radio Standards Laboratory, in which two photon
processes give a fast fluorescence as well as the previously observed delayed
fluorescence due to exciton-excitor collisional recombinations. Preliminary
work on detection of high-frequency beats from two closely spaced gas laser
lines in the infrared was started.

Work was begun on an apparatus to measure the acceleration of gravity
using an interferometer (one plate of which is the falling object) together
with a gas laser light source. In addition to the importance of this meas-
urement to the field of standards, possible variations in the gravitational
field strength (which could be of cosmological origin) might be detected
with the high precision obtainable with this new technique.

Plasma Physics, Statistical Physics, and Aerodynamics. An ex-
perimental study was made of the structure of self-ionizing hydromagnetic
shock waves in a magnetic field. Experiments are planned to apply hydro-
magnetic shocks to the study of solar flares.

Data Center on Atomic Collision Cross Sections. The Data Center
completed its survey of all literature reporting cross sections for two-
body collisions involving a free electron, and is currently providing bib-
liographic searches for the general scientific community. The material is
coded by subject matter as well as by normal reference to author, journal, etc.
Preparation for the publication of the complete bibliography by subject
classification is in progress. The Data Center has been jointly financed
by ARPA, ONR, and NBS.

2.2. CHEMISTRY AND PROPERTIES OF

MATERIALS

2.2.1. ANALYTICAL AND INORGANIC CHEMISTRY

Recent scientific and technological advances require new, accurate data
on the properties of materials. To help fill this need, the Bureau conducts
intensive investigations to determine the physical and chemical properties
of both common and rare elements and compounds. Such investigations
require new and improved analytical techniques as well as tried and proved
methods. New instrumental analyses hold promise for improved analytical
speed, accuracy, and precision.

Consultant services are available to Government and industry alike on
diverse subjects such as radioactivity (the Bureau participates in the Atomic
Energy Commission's standards program), the compilation of scientific and
technical data, the measurement of physical constants and chemical proper-
ties of materials, and the preparation of standard samples. The Bureau also

issues standard materials of known composition for metallic and nonmetallic
inorganic compounds as well as standards of composition for some organic
materials.

New activities include a study of inorganic synthesis and reaction rates,
an analysis of trace impurities and their effect on the properties of materials,
the preparation of standards required for determining atomic weights by
isotopic abundance measurements, and a study of optical and X-ray spectra
in crystals at low temperatures.

Atomic Weight Redetermination. Atomic weights of several ele-
ments are being redetermined with increased accuracy by employing mass
spectrometric methods of comparing natural materials with reference stand-
ards prepared from concentrates of individual isotopes. Extracting a given
element from a wide variety of natural sources in order to establish a normal
value for its atomic weight is an important part of the program. The work
of redetermining the atomic weight of copper is nearly complete, and pre-
liminary work for redetermining the atomic weights of other elements,
especially bromine, is now in progress.

Reactivity of Coordination Compounds. Studies of coordination
compounds are being conducted to determine the role of these substances as
catalysts and reaction intermediates, and to investigate their application to
the synthesis of new compounds. As part of these studies, isotopically en-
riched boron compounds are employed to study the displacement of one such
compound from a complex by another compound. In addition to providing
information about the reactivity of boron coordination compounds, these
studies suggest several possibilities for solving problems of synthesis in boron
chemistry.

Thermodynamics of Aqueous Solutions. Studies of thermodynamic
constants of acids, bases, and salts and their interactions in solution provide
basic knowledge essential for improving and extending existing methods of
measurement. A new technique, isopiestic vapor-pressure measurements,
when applied to a water-urea-sodium chloride system yields free energies or
chemical potentials of each of the three components at all compositions up
to saturation; that is, up to about 47 percent urea and 14 percent sodium
chloride. From the free energies obtained, the effect of added urea on the
solubility of sodium chloride and the effect of added sodium chloride on the
solubility of urea can be calculated. The composition of the solution at the
point of mutual saturation (where the solution is saturated with respect to
both urea and sodium chloride) is then readily derived.

pH Scale for Alcohol-Water Solvents. Because of its reproduci-
bility, determining the pR of alcohol-water solutions found with commercial
electrometric pH equipment is an important control variable in many indus-
trial and research operations. Determined in the conventional way, pH num-
bers are interpreted in terms of hydrogen ion concentration or activity only
when the solvent medium is pure water. A scale of pH (designated pH*)
for methanol-water and ethanol-water media has been proposed, its practi-
cability has been demonstrated, and procedures for assigning standard pH*

values to reference solutions have been devised. The pH* determined ex-
perimentally bears a simple relation to dissociation constants and other
thermodynamic quantities in the same medium and, as such, should have
wide application in many branches of chemistry and biology. Furthermore,
scales of pH* can be established for many other solvent systems by similar
procedures.

Dielectric Cryometry for Determining Purity, The purity of a
compound can be determined by measuring the temperatures corresponding
to particular solid-liquid ratios while the compound melts or freezes. In a
method called dielectric cryometry recently investigated by the Bureau, the
solid-liquid ratio is determined by measuring the change in dielectric co-
efficient, and by simultaneously measuring corresponding temperatures dur-
ing the melting process. The data collected indicate a change in an intensive
property of the material, and samples of only 4 to 10 milliliters are required.
Purity measurements, made on a number of compounds with diverse dipole
moments and polarizabilities, resulted in a precision of 0.005 to 0.0004 mole
percent. Refinements in the design of the apparatus may increase the
precision still further.

Argon Shielding in Spectrochemical Analysis, Spectrochemical
analysis of high-temperature alloys is difficult because given elements vola-
tilize at different rates depending on whether they are present in an iron-,
nickel-, or cobalt-base alloy. Standards for the same element in all three

Isopiestic vapor pressure measurements provide a new technique for measuring
the thermodynamic properties of aqueous solutions containing one electrolyte
and one non-electrolyte. The wire apparatus is used to close the covers on the
sample cups while they are still under vacuum in the dessicator. (See p. 91.)

Laser microprobe can perform a spectrographs analysis of a sample as small
as 50 microns in diameter. (See p. 93.)

types of matrix are therefore necessary. Shielding the specimens with argon
gas reduces the differences in volatilization rate and shows promise of re-
ducing the number of spectrochemical standards needed for the routine
determination of the major constituents in high-temperature alloys.

Transition Probabilities. Transition probabilities are important to
analytical chemistry and basic spectroscopic research. Most transition prob-
abilities determined to date have been for gaseous elements that are easily
introduced into an arc discharge. However, through exhaustive studies of
the properties of the gas-stablized arc, data for 105 lines in the spectrum of
neutral atomic iron have been redetermined. An analysis of the new data
has resulted in transition probabilities for neutral atomic iron more precise
than those obtained in three earlier investigations.

Laser Microprobe. A prototype of a commercial laser microprobe is
being investigated and, with certain changes, is expected to be a useful
tool in microanalysis. The instrument permits spectrographs analysis of
samples as small as 50 microns in diameter. A brief, high-energy pulse

of light from a ruby laser, focused through a microscope onto the spot to
be analyzed, is sufficient to volatilize the sample as a jet of vapor. This
vapor jet, passing through a gap between two graphite electrodes connected
to a large condenser, triggers a spark discharge which excites the elements
in the sample. The spectra characteristic of the light from the spark dis-
charge are recorded with a spectrograph in the usual way. Almost all
the elements in the periodic system may be excited simultaneously. In
addition to its application to the analysis of small samples, segregates, and
inclusions, the laser microprobe is expected to be valuable for studying high-
purity materials. An advantage of the device is that it requires little or no
preparation of the sample prior to the analysis.

Solvent Effects on the Rates of Acid-Catalyzed Reactions. The
speed of chemical reactions in solutions is influenced by the nature of the
solvent, particularly when an acid or base takes part. For example, the
rate of a reaction, catalyzed by acid, may change because of the effect
the solvent produces on the acidity of the medium or because the free
energy of activation is altered. The rate of hydrolysis of acetal, a typical
acid-catalyzed reaction, was studied in solvents prepared by mixing water
with varying proportions of acetone, dimethylsulfoxide, dimethylformamide,
or A^-methylpropionamide. Replacement of half of the water by acetone
caused the rate to fall to %5 its value in pure water; and similar amounts
of dimethylsulfoxide, dimethylformamide, and A^-methylpropionamide re-
duced the rate to *40, %5» an(^ %oo? respectively. The mechanism of the
solvent effect is still not clear, but the change in rate does not appear to be
linked closely with the change of either the dielectric constant or basicity of
the medium.

Acidities of Dinitrophenols in Benzene and Water. Quantitative
comparisons of the behavior of acids and bases in two dissimilar solvents
like benzene and water furnish valuable insight into the mechanism through
which solvents affect chemical reactivity. Six dinitrophenols, all having
the same composition but differing in atomic arrangement, have ionization
constants in water ranging from approximately 10"4 to 10"7, as shown by
careful spectrophotometry measurements of the acid strength. However,
the relative order of acidic strengths in benezene differs from that in water.
Information of this type is helpful in interpreting the behavior of dinitro-
phenols in nonaqueous solvents, where they are finding increased use as
reference acids.

Crystal Growth From Mixed Solvents. Solvent effects on the growth
of large crystals from solution have recently been illustrated in experiments
with oxalic acid. For example, anhydrous oxalic acid crystallizing from
glacial acetic acid solution gives inferior single crystals containing inclusions
of the mother liquor. However, the addition of small amounts of water
added to the solvent produces single crystals of greatly improved quality,
and nucleation is inhibited. A phase study of the system oxalic acid-acetic
acid-water at 50 °C showed that anhydrous oxalic acid is the stable solid
phase in equilibrium with aqueous acetic acid solutions containing up to

5.2 percent water. In other experiments, single crystals of oxalic acid
dihydrate, difficult to grow from water solution, were of good quality when
grown in acetone-water mixtures.

Studies of Crystal Symmetry. A general study on the effect of homo-
geneous strain on crystal symmetry has shed light on the problems of internal
friction due to point defects, second-order piezoelectric coefficient, second-
order transformations, solid solution effects, and crystal field phenomena;
and has suggested procedures for space-group determinations from ambiguous
X-ray patterns. The treatment is general and applies to all crystalline solids
with any type of strain.

X-Ray Analysis of Crystalline Solids, A high-voltage (150-kv) , fine-
focus X-ray apparatus with a special collimating slit has been procured to
obtain X-ray diffraction diagrams of single crystals up to 1 in. thick. Con-
ventional diffraction procedures can be applied only to thin crystals or to
surface layers of specimens. The X-ray unit has also been used to obtain
diffraction patterns of single crystals enclosed by protective containers of
Pyrex glass.

X-ray diffraction pattern of germanium single crystal obtained with high-voltage
fine-focus X-ray unit. This special equipment can be used to explore single
crystals up to 1 inch thick. (See p. 95.)

Control of Fractional Distillation, Variations in ambient tempera-
ture, barometric pressure, and line voltage affect the efficiency of fractional
distillation in the laboratory, principally because these variations cause
changes in the flow rate of vapor from the still pot to the column. An auto-
matic controller, consisting of a thermistor sensing device in the vapor line,
automatically regulates the heat input to the still pot, thus maintaining a
constant flow of vapor to the column. With the use of this device, the
fractionation process can operate at an appreciably higher, uniform efficiency
throughout the distillation.

Moisture Determination, A gas chromatographic method was devel-
oped for determining water content in various materials, particularly in
grain. A solution formed by extracting the moisture from the material with
methanol is injected into a commercial gas chromatograph. Methanol and
water curves are recorded on a strip chart by the gas chromatograph and
the relative areas under the methanol and water peaks are used to calculate
the moisture content. The method is precise and accurate to 7 parts in
one thousand, corresponding to an accuracy better than 0.1 percent of the
water content of a typical grain containing about 14 percent moisture.

2.2.2. PHYSICAL CHEMISTRY

The Bureau conducts a broad program of basic research in physical chemis-
try. The primary objective of this program is the development of an under-
standing of the molecular basis for macroscopic properties and processes.
Particular emphasis is placed on (1) the analysis of relatively complex
reactions into elementary molecular processes, (2) the development of the
energetics of simple chemical reactions, and (3) the determination of ac-
curate structural parameters of reactive molecular species. Research is con-
ducted in such areas as the kinetics of very fast reactions at high temperatures,
the photosynthesis of labeled organic molecules, the structure of reactive
molecules which are stabilized in inert matrices at cryogenic temperatures,
the interaction of high-energy radiation with organic molecules, the deter-
mination of absolute isotope abundancies, the fundamental processes related
to surface catalysis, the structure and stability of short-lived species occurring
in high-temperature combustion processes, and reaction mechanisms in syn-
thetic organic chemistry. Supporting theoretical studies are made in the
general fields of relaxation and transport phenomena, mechanisms of ex-
citation and deactivation of simple molecules, energy distribution in and
dissociation of excited organic molecules, and molecular orbital calculation.
Considerable effort is directed to the development of special instrumentation
and associated techniques of measurement.

The need for critically evaluated fundamental data continually increases
at an accelerated rate. During the year a new project was initiated with the
objective of developing a simple system for collecting, coding, retrieving,
and assessing basic data in selected areas of physical chemistry. This project
represents an initial phase in the establishment of a special data-processing
activity at the Bureau.

Thermochemistry. During the past year the Thermodynamic Data
Group commenced a full-scale revision of NBS Circular 500, Selected Values
of Chemical Thermodynamic Properties, which contains best values of the
heats and free energies of formation of inorganic substances and some or-
ganic compounds for which data were available at the time of publication
(1952). The current revision will take into consideration all available data
through 1961. This program on compilation of standard reference data
in the area of chemical thermodynamics has been a continuing part of the
Bureau's activities since 1940, with assistance from the Office of Naval
Research and the Atomic Energy Commission.

Recent experimental developments have been in connection with the design
and construction of two new high-precision calorimeters. An adiabatic
solution calorimeter which has a platinum reaction vessel and which can be
operated at temperatures to 100 °C will be used for measurements of the heats
of solution of refractory oxides and other relatively insoluble materials. The
assembly of this apparatus is complete and preliminary tests will be started
soon.

An adiabatic rotating-bomb calorimeter is also under construction. This
bomb consists of layers of silver and stainless steel, with an internal liner of
platinum. The bomb and jacket have been built, and construction of the
mechanism to rotate the jack, bomb, and adiabatic shield is now in progress.

Kinetics of Ion Decomposition. Certain unimolecular ion decompo-
sition processes are readily observable in a magnetic sector mass spectrometer.
These include processes whose decomposition rates are of the order of 106
sec-1. The occurence of such slow decomposition processes in small poly-
atomic ions is of considerable theoretical interest. Recently, such processes
have been observed in ionized molecules of hydrogen sulfide and completely
deuterated methane. The substitution of various hydrogen isotopes pro-
duced pronounced effects on the occurrence of such processes. With de-
uterated methane, substitution of one or more hydrogens for deuterium in
the ion completely suppresses decomposition. Another study performed with
this mass spectrometric technique has given useful information on the prob-
lem of energy equilibration in excited polyatomic ions. It was found that
the mode of decomposition of an excited ion was independent of its past
history. This result supports the validity of the quasi-equilibrium theory of
mass spectra.

Field Emission. Recent field-emission studies on the adsorption of
carbon monoxide on tantulum and niobium reveal the complexity of the
process. It has been found, for example, that there are at least three
binding energy states for chemisorbed carbon monoxide on tantalum, and
at least two for carbon monoxide on niobium. In general, the similarity
found for the adsorption behavior of carbon monoxide on these two metals
is very pronounced. There is no detectable difference between adsorption
by niobium in the superconducting as compared to the normal state.

High-Temperature Microwave Spectroscopy. A microwave spec-
trometer which can be operated at temperatures up to 1000 °C has been

The rapid and homogeneous heating of gas samples by shock waves provides a
powerful tool for the study of fast reactions at high temperatures. (See
p. 99.)

constructed in a program supported by the Advanced Research Projects
Agency. This instrument permits the extension of powerful microwave
techniques to the identification and structure determinations of molecules
and radicals which are present in high-temperature systems. There are
numerous problems in high-temperature chemistry for which important
information can probably be obtained by this technique. Spectra have
been detected and analyzed for such molecules as aluminum monoflouride
and aluminum monochloride, which do not exist at room temperature, but
which are important constituents, for example, in rocket combustion systems.
The microwave spectrum of lithium chloride vapor was also observed for
the first time-

Enolization and Isomerization Reactions of Reducing Sugars,
Numerous investigations over the past 60 years have shown that reduc-
ing sugars in alkaline media undergo reversible enolization and that the
resulting enediols are intermediates in a variety of rearrangement, elimi-
nation, and condensation reactions. The use of recent tracer techniques
employing carbon 14 and tritium-labeled sugars makes it possible to follow
reaction paths, to measure rates of reaction, and to determine the propor-
tions of products formed.

A broad study of the enolization reactions of the principal pentoses,
hexoses, and heptoses is now in progress. Striking differences have been
found in the rates at which the various sugars of an epimeric group are
formed, and in the effect of various catalysts on both rate and course of
the reaction. For example, in rearrangements catalyzed by sodium hydrox-
ide, D-glucose is enolized more rapidly than D-mannose, and the rate of

conversion of D-glucose to D-fructose is five times that of D-mannose to D-
fructose. But when pyridine is the catalyst, the rates of enolization are re-
versed, and the conversion of D-mannose to D-fructose is three times as rapid
as that of D-glucose.

Generally, the 1,2-enediol reverts to the corresponding ketose more rapidly
than to the epimeric aldoses. The 2-ketoses then yield both 1,2- and 2,3-
enediols. Relative rates of 1,2- and 2,3-enolization are being studied by
quantitative determination of the rearrangement products of 2-ketoses con-
taining five, six, and seven carbon atoms. Heretofore, unknown 3-keto
sugars have been postulated as intermediate in the production of 3,4-enediols.
The recent preparation of crystalline D-77ia/i/io-3-heptulose has provided ma-
terial for direct study of 3,4-enediols. On treatment with alkali, the new
compound gave D-g/wco-2-heptulose, by way of the 2,3-enediol; and, of even
greater interest, D-allo- and D-ai£ro-2-heptulose. Formation of the last two
substances requires reversible 3,4-enolization followed by 2,3-enolization.

Cryogenic Surface Chemistry. The reactions of hydrogen atoms
with condensed olefins have been under continuing investigation to develop
an understanding of chemical reactivity at low temperatures. This research
has led to a clarification of several aspects of the chemical and physical
processes involved, among which are the establishment of the position of
addition of the H atom, the effect of diffusion on the reaction products, and
the mechanism of the reaction after the initial step. An important result
was the demonstration that, in the H atom addition to the butene at low
temperatures, cw-butene-2 is not formed. This finding permits a detailed
examination of the disproportion atom-recombination reactions of the s-butyl
radicals, starting with cw-butene-2 as reactant.

Kinetic Isotope Effects. A convenient method was developed for
measuring isotope effects of tritium in reactions that yield water-J. The
water-J is sublimed and the isotope effect is obtained from the ratio of the
molar radioactivity of the sublimed water to that of the initial reactant. This
procedure is being applied to the study of a wide variety of organic reactions.

Shock-Wave Studies of Vnimolecular Reactions. The rapid and
homogeneous heating of gas samples by shock waves gives kineticists a power-
ful tool for the study of fast reactions at high temperatures. A single-pulse
shock tube is being used to study chemical reactions in the temperature range
700 to 1500 °C. In such an instrument the passage of a reflected shock
wave heats a gas sample to a high temperature; about a millisecond later, a
strong rarefaction wave drastically lowers the temperature, thus quenching
the various chemical processes after an accurately known time interval. Con-
ventional analytical methods, such as gas chromatography, may then be used
to study the nature and extent of the reactions. Current work is concen-
trated on studies of simple unimolecular decompositions resulting in stable
molecules. It has been possible to extend the range of kinetic studies pre-
viously carried out at low temperatures and to impose a critical test on the
postulated mechanisms and rate constants. Useful data have been obtained
for the tert-buty\ chloride, bromide, and alcohol decomposition reactions.

Except in the case of alcohol the results confirm those of earlier studies which
used quite different methods, and give valuable evidence of the accuracy of
the single-pulse shock-tube technique.

Ionization Processes at Surfaces. The studies of ionization on re-
fractory metal surfaces at high temperature have been extended to the meas-
urement of the lifetimes of cesium, rubidium, sodium, and potassium ions
on rhenium surfaces as a function of temperature. A general type of poten-
tial function with an attractive and repulsive term has been fitted to the
data, and trends with size of the positive ion have been determined. The
characteristics of the surface ionization process can now be predicted with
regard to both ion size and charge.

Polycyclic Ketones. Polycyclic ketones, derived from inositol by oxi-
dation, bridge the gap between the cyclitols and certain biologically im-
portant phenols. Because of their reactivity, very few of these important
intermediates have been isolated. In a project sponsored by the Division
of Air Pollution, Public Health Service, it was found that the residue, after
nitric acid oxidation of mjo-inositol and separation of known products, con-
tained a new substance, shown to be D-L-#yZo-trihydroxycyclohexenediolic
acid. The substance, the enolic form of a diketo inositol, is readily oxidized
to a new trihydroxycyclohexanetrione. With basic catalysts, the acetate of
the enediolic acid can be aromatized and converted by hydrolysis to
pentahydroxybenzene, an important substance not generally available nor
closely investigated. This synthesis opens up a promising area for study.

These crystals of D-manno-3-heptulose monohydrate, the first pure crystalline
3-keto sugar to be prepared, will provide Bureau scientists with an opportunity
for direct study of this and related sugars. (See p. 100.)

100

Acetylation of the new trione under acidic conditions gave an unexpected
tricyclic condensation product, the chemistry of which is being investigated.

Vacuum Ultraviolet Photochemistry. The interaction of vacuum
ultraviolet radiation with various molecules is being investigated under
extremes of temperature and pressure in order to understand the chemistry
of fragments of molecules. The CH3CH fragment has been found to decom-
pose to give Ho and acetylene, as well as to rearrange to form ethylene.
The effects of energy of the exciting radiation can best be studied in vacuum
ultraviolet photochemistry by using pure, intense line sources. Source
technology has been advanced by studying emission of rare gas resonance
lamps under varying conditions of temperature, pressure, filling gas, and
additives.

High-Temperature Surface Reactions. The increasing use of re-
fractory metals in military and civilian technology requires considerable
understanding of the physical and chemical behavior of these metals. The
high-temperature surface reactions of chlorine and bromine with nickel repre-
sents an active area of investigation in which chemical kinetic effects are
being studied. A highly successful technique has been developed in which
the products of reaction are sampled with a time-of-flight mass spectrometer.
The reaction surfaces may be either those of a single crystal or polycrystalline
material. The mechanism of the nickel-bromine as well as the nickel-chlorine
reaction has been established. In either case, the reactive monohalogen
species has been found to be an important product in the higher temperature
region. This work is conducted under the sponsorship of the Atomic Energy
Commission.

Radiolysis of Simple Hydrocarbons. The gas-phase radiolysis of
single hydrocarbons, at pressures up to the critical pressure, was investigated
with Atomic Energy Commission support. It was shown that, in all cases,
the unimolecular decomposition of parent ions and of electronically excited
neutral molecules contributes to the formation of observed products. In
the radiolysis of propane at one atmosphere, the primary fragmentation of
the parent ion shows a good correspondence to the recently calculated 10~10
second breakdown pattern, while the modes of decomposition of the neutral
excited molecules are similar to those observed in the vacuum ultraviolet
photolysis. It has been firmly established that accurate relative rate con-
stants of ionic reactions occurring at atmospheric pressure can be obtained,
so that radiation chemistry can now be considered as complimentary to mass
spectrometry in the study of ionic reactions. This has been especially
demonstrated by the following studies: (1) Determination of the relative
rate constants of hydride ion and proton transfer reactions between ethyl
and propyl ions and a number of organic compounds; (2) the study of the
reactions of CH5+ and H3+ with hydrocarbons to form carbonium ions. The
latter type of reaction, which has not yet been observed in the mass spectrom-
eter, is of considerable importance in radiation chemistry because such reac-
tions may be expected to occur between a large number of protonated parent
molecules and neutral molecules.

101

Standard Reference Data in Physical Chemistry. An investigation
of document retrieval systems which will assist in the review and critical
assessment of physico-chemical data is now in progress. A selected library
of documents — primarily reprints and reports — is being coded by "descrip-
tors" and accession numbers and filed as a deck of optical coincidence or
peek-a-boo cards. At the present time this library amounts to about 3000
documents. No thesaurus of terms has been established, so the number of
descriptive terms is currently of the order of 20,000 words, including author's
names. The present method of retrieval is manual (light screen and an over-
lay grid), but a Microcite information retrieval machine, developed by the
Basic Instrumentation Laboratory, is being constructed. This system is de-
signed to support a broad program for rapidly collecting and assessing data
in the physical sciences. The general approach consists in selecting narrow
areas of traditional fields of research, assigning reviewers who are acknowl-
edged authorities in the prescribed fields, and providing the mechanical assist-
ance required for document search and reproduction. Subjects for such crit-
ical reviews are selected from the major areas of physico-chemical research;
for example, chemical kinetics, mass spectroscopy, transport properties,
thermodynamics, molecular spectroscopy, radiation chemistry, and surface
processes. The reviews will include sets of critically evaluated data which are
internally consistent and which can be regarded as "best" values.

2.2.3. INORGANIC SOLIDS

The demand for nonmetallic inorganic solid materials capable of with-
standing extreme environmental conditions constantly increases as scientific
and space technology advances. The Bureau provides data, techniques,
and reference materials to help solve measurement problems in this field of
research. Methods for producing and characterizing metallic oxides, glasses,
and inorganic nonmetallic crystals have been investigated and data on the
properties of many of these materials have been provided. Significant ad-
vances were made during the year in developing techniques for studying
the physical properties of crystalline solids over wide ranges of pressure
and temperature.

Rare Gas Crystals, A deeper understanding of the mechanisms and
problems involved in growing large single crystals for industrial and scien-
tific purposes may be gained by studying simpler substances first. Such
crystals are formed from the rare gases argon, krypton, xenon, and neon.
In current Bureau experiments, argon and krypton crystals are grown near
the triple points of these elements, 84 and 116 °K respectively. These studies
correlate crystal size and shape, growth rate, temperature gradient, and
degree of supersaturated solution with theory, and show that large rare gas
crystals may be prepared and studied with many of the same techniques
used at higher temperatures on other substances. For example, etch pat-
terns in polycrystalline argon at 77 °K have been studied to learn about grain
growth, recrystallization, and annealing; and have been compared to the

102

Surface of a thermally
etched polycrystal of
argon. The rare gases
form very simple crys-
tals and so are more
readily studied to gain
a deeper understand-
ing of the mechanisms
and problems involved
in growing crystals.
Diameter of the field
of view is 2 mm. (See
p. 102.)

same processes in metals, where these phenomena take place at much higher
temperatures.

Rare gas crystals are perfectly transparent in a broad spectral range,
from the infrared to the ultraviolet. Spectroscopic techniques are em-
ployed to show the location of small amounts of impurities within a crystal
lattice, how they get there, and how they diffuse. These impurities have
large effects on the physical properties of crystals.

Molar Volume of Solid Neon Isotopes. Solid neon, like other rare
gas crystals, serves fairly well as a model "simple solid." Of the two more
abundant neon isotopes, the lighter has a larger zero-point energy (import-
ant in determining thermodynamic properties) and may be expected to have
a slightly larger molecular volume than the heavier. X-ray diffraction meas-
urements, recently completed at the Bureau, provide values for the lattice
constants of the two isotopes throughout most of the temperature range in
which they exist as solids (0 to 25 °K) , and show this is to be true. Ther-
mal expansion coefficients have also been computed and used to calculate
the Griineisen constant, which increases slightly in this temperature range.

Crystalline Forms of Bismuth Oxide. Bismuth oxide (Bi203) is
assuming an increasingly important role in the ceramics industry as a con-
stituent of glasses of high refractive index, glazes with excellent bonding
capabilities, and ceramic bodies having special nuclear and electronic appli-
cations. Various crystalline forms of bismuth oxide are being studied, as
well as their reactions with other oxides.

In this work, various forms of bismuth oxide and the effect of adding 33
selected oxides to these forms were studied by means of high-temperature
X-ray and differential thermal analysis. The first part of the studies showed
that bismuth oxide possesses two stable and two metastable forms; the con-

714-691 O— 64 8 103

ditions for these formations were determined. In the oxide-addition portion
of the study, phase diagrams showing the relationships between temperature,
composition, and phases present were constructed. The results clarified pre-
viously conflicting findings and provided a background of fundamental new
data.

Random Network Models for Liquid and Glass Studies, Bureau
scientists are studying the molecular arrangement of silica glass and liquid
water by employing wire random network models of the type first made at
the Bureau about 1957. The concept of a "random network theory" has
been discussed qualitatively, but the only previous structural models receiving
detailed quantitative consideration have been unrealistic complex arrange-
ments of high symmetry.

In the present study, the models are synthesized according to a set of rules
representing the conditions of a real condensation process. Normal con-
densation leads to the random network, but if a single six-membered ring
of the crystalline structure is present as an initial nucleus, then the condensa-
tion process leads to the crystalline structure entirely.

For the quantitative study of the statistical topology and geometry of these
new models, high-speed computer techniques are being used. At present the
data are obtained by determining the coordinates of each unit in the actual
physical model, but better statistical data may be obtained eventually from
larger models whose synthesis is entirely mathematical.

Determining positions of structural units in a random tetrahedral network rep-
resenting molecular arrangements in such important materials as silica glass
and liquid water. Understanding the structure of such materials would shed
much light on their properties. (See p. 104. )

104

Vapor-Pressure Studies, A program for defining the general prob-
lems involved in making precipe vapor-pressure and heat-of-vaporization meas-
urements, seeking solutions to these problems, and applying new techniques
to vapor-pressure measurements of the platinum metals group is being con-
ducted at the Bureau with the support of the National Aeronautics and Space
Administration. A vacuum microbalance technique has been developed
and applied to heat-of-vaporization and vapor-pressure measurements of
platinum, iridium, rhodium, palladium, ruthenium, and osmium at tempera-
tures near 2500 °K. Measurements of the latter two elements have been
completed during the year.

Improved measurement techniques have successively increased the preci-
sion and accuracy of the data obtained in the studies. As a result, sources
of measurement error originally masked by the scatter of the data and thought
to be insignificant are now detectable.

Attempts to measure vapor pressures of the platinum metals in the range
of 10-12 atmospheres (atm) resulted in an abnormally low vaporization rate,
as the substance evaporated into a vacuum of about 10~9 atm. Impurities such
as oxygen or carbon may form a stable layer on the surface of these sub-
stances, thus inhibiting the vaporization process, but a much more thorough
investigation must be undertaken before definite conclusions can be drawn.

Crystal Structure Determinations, In studying the structure of mat-
ter by X-ray diffraction, several compounds have shown interesting and un-
usual characteristics. For example, the structural determinations of barium
tetraborate (BaB407) revealed an unusual, previously unknown, boron-oxygen
network consisting of well-known subunits of linked six-membered boron-
oxygen rings. Half of the boron is tetrahedrally coordinated and half is
triangularly coordinated. The barium-oxygen and barium-barium distances
correlated very well with the cation distribution in glasses as determined by
X-ray radial distribution studies.

The structures of sodium trimetaphosphate (Na3P309) and sodium trimeta-
phosphate monohydrate (Na3P309-H20) are unusual in that the hydrate has
the same basic structure as the anhydrous salt, although the material is
not zeolitic. Other structural investigations were recently completed on
1-ethyldecaborane, lithium dipotassium trimetaphosphate monohydrate
(LiKsPsOg-F^O), and sodium tetrahydroxyborate dihydrate (NaB(OH)4*
2H20), whose structure was determined by a direct method which tested
new phase determination equations.

Phase Change Studies of Silica-Metal Oxide Systems. Phase
changes in silica-metal oxide systems result in varying degrees of opalescence.
Such changes, noted in immiscible liquid studies, may have application in
improved turbidity standards.

In the immiscibility studies, lowering the temperature of a homogeneous
mixture of liquids to a particular critical temperature caused a new liquid
phase to appear as droplets at many points throughout the liquid. These
droplets subsequently coalesced into larger droplets and finally formed a
separate immiscible layer. If a homogeneous liquid mixture is cooled below

105

its particular critical temperature, the new liquid phase occurs spontaneously ;
yet the high viscosity of the homogeneous mixture at this temperature in-
hibits coalescence, allowing the early stages of phase separation to be observed.

Phase change studies at the Bureau, conducted in silica-metal oxide sys-
tems, show that, aside from droplet-shaped phases, a continuous fibrous
network is formed. This fact suggests the presence of a nucleating polymer
network in the homogenous melt before phase separation occurs. A study
of these nucleating phenomena, and of the subsequent coalescence process,
shows that glasses having a controllable degree of light scattering can be
produced. Glasses of this type are being evaluated as turbidity standards
to replace less durable plastic and liquid standards presently in use.

Standard Glasses for Viscosity Measurements. Standard glass No.
710 (soda-lime-silica) has been issued as a standard for calibrating com-
mercial glass viscometers. Another glass No. 711 (lead-silica) is now be-
ing processed and will soon be ready for domestic and foreign distribution
as a second viscosity standard. Laboratories carrying on extensive research
programs, and laboratories committed to routine physical properties meas-
urements, have created a strong demand for standard glasses of this type.

A second series of glasses, two- or three-component glasses of high purity,
will be made for use in studies concerning the constitution of glasses.
Through systematic studies on properties of simple glasses from a common
source, information can be gathered and correlated to give positive results
and interpretations concerning the structure of glass.

Elastic Constant Data. The Bureau conducts a program of refining
and improving methods of determining elastic constants of various materials.
In determining such values for rutile (Ti02), three of a set of six values
disagreed with values reported elsewhere. Subsequent checking showed
that if the values used in the previous work were corrected for their crystal-
lographic orientations, good agreement could be obtained. The values for
rutile are now regarded as well established.

Velocity of sound measurements should be made along symmetry axes
in cubic crystals because the resulting equations for computing elastic con-
stants are then much simpler. The Bureau has put the equations into a
form suitable for use along any axis. These equations have been tested
by redetermining values of the elastic constant of strontium titanate, and
good agreement was obtained with previous values. This method has been
used to determine the elastic constants of uranium dioxide.

Structural Studies of Materials Under High Pressures. Many ele-
ments and compounds may be changed from one crystalline form to another
by varying the temperature or pressure or both. This phenomenon, gen-
erally known as polymorphism, is more specifically known as allotropism
for the elements. Phase transformations occur more often with pressure
variation than with temperature variation. Until the crystal structure of
these polymorphs is determined, data on the physical properties of the high-
pressure phases are of limited value.

106

Left: X-ray diffraction camera which incorporates an opposed diamond-anvil
pressure cell. Right: Matched X-ray powder diffraction patterns of potassium
iodide showing high- and low-pressure forms. Left half represents the normal
face-centered cubic structure at 1 bar. Right half, at 20 kilobars, shows a
simple cubic structure. The pattern of the salt is shown by the rings and
arcs. The spots are due to diffraction from the diamonds. (See p. 106.)

The Bureau has developed an X-ray powder diffraction camera for ob-
taining structural information on materials subjected to pressures as high
as 70 kilobars. This technique is useful for showing that a real trans-
formation exists, particularly in those cases where other techniques, such
as electrical resistance and density measurements, either give ambiguous
results or erroneously indicate the absence of real transitions.

In applying this high-pressure device to studies of the alkali halides,
potassium and rubidium halides and also cesium fluoride, were all shown
to have a sodium chloride-type structure at 1 atm and 25 °C, and convert
to a cesium chloride-type structure at elevated pressures.

Other studies on some rare-earth metals have shown that allotropy exists
in lanthanum, cerium, praseodymium, and neodymium at elevated pres-
sures. The structure-types of these rare-earth allotropes are being deter-
mined.

107

Mechanical Properties of Ceramic Bodies. Many mechanical prop-
erties of brittle polycrystalline bodies are extremely structure-sensitive.
Knowledge of this structure sensitivity is essential to intelligent measure-
ment and control of the mechanical properties of such materials. To help
meet this need, the Bureau, partially supported by the Atomic Energy
Commission, conducts studies of the influence of microstructure on the
strength and elasticity of brittle polycrystalline bodies — in particular, ceramic
bodies.

The strength of such bodies strongly depends on their grain size and
the minimal degree of continuity within them, the latter being thought of
in terms of porosity. Only the very general trend of this dependence was
previously known, namely that their strength decreases with an increase in
either porosity or grain size.

In the present study, a more definitive approximation of this depend-
ence was formulated. For example, the studies showed that the strength
of porous brittle polycrystalline bodies decreases approximately loga-
rithmically with both increasing porosity and a logarithmic increase in
grain size. This approximation is applicable for ceramic bodies of alumina.
beryllia, magnesia, thoria, urania, and chromium carbide. The approxi-
mation, expressed in equation form, is gaining some acceptance in the
field of ceramics as a useful empicism.

Other efforts in the present study have been toward developing a micro-
graphic measure of the minimal degree of continuity within ceramic bodies.
Such a measure has been developed and is being utilized at present to
derive a truer and less empirical representation of the structure sensitivity
of the strength of brittle polycrystalline bodies.

2.2.4. METALLURGY

Metallurgical research is directed primarily toward increasing our under-
standing of the properties of metals in order to encourage the optimum use
of existing metals and alloys and to stimulate the development of new ones
having desirable properties. Broad programs of fundamental and ap-
plied research are conducted which attempt to relate the macroscopic prop-
erties of metals and alloys to their known structure. Crystal structure
and the role of dislocations and point defects are of primary importance.
although in some cases more gross structural features such as grain size,
shape, and distribution are investigated. The electronic structure of metals
and alloys is investigated to obtain basic knowledge on the cohesion of
metals. Important phenomena in metallurgy such as diffusion, crystal
growth, fatigue, plastic deformation, and corrosion are studied intensively,
and explanations in terms of atomic mechanisms are developed.

The metallurgy laboratories also provide advisory services to other Gov-
ernment agencies, particularly in connection with the investigation of serv-
ice failures of transportation equipment. Participation in the Bureau's
standard samples program by the development of specific standards of
gases in metals is another activity.

108

Metal Fatigue Investigated in Aluminum Alloys. In a recently
completed investigation of the effect of environment on the fatigue strength
of aluminum alloys, tests were conducted in which the humidity was changed
during the test. Although a high-humidity atmosphere is detrimental to
fatigue strength, the results of this investigation showed that the environ-
ment during the initial part of the test has no effect on the total number of
cycles to fracture. As stressing is continued beyond this initial period,
fatigue cracks develop rapidly if moisture is present and slowly if the
atmosphere is dry.

Many of the fracture surfaces of the specimens tested in this investi-
gation showed small areas of brilliant color. Optical and electron micro-
scope examination disclosed that the colored areas had marked striations,
due to the progress of the crack front with each cycle of loading. Where
the striation spacing was about equal to the wavelength of visible light,
the surface served as a diffraction grating to produce the observed colors.

Properties of Metals at Elevated Temperatures. Creep tests, made
below 1200 °F on cold-drawn and aged specimens of a nickel-aluminum
alloy, showed that the creep properties of the metal were improved by prior
cold-drawing. Additional improvements were obtained by aging the speci-
mens prior to testing in creep. Conformance to current theories of defor-
mation was obtained only over limited ranges of temperatures and stresses,

Observing colored areas on a metal fatigue fracture surface, NBS scientists
took electron micrographs to determine the microscopic structures responsible
for the color effect. They found that striations are caused by the intermittent
progress of the crack front with each cycle of load; where the spacing is suffi-
ciently regular, the surface behaves like a diffraction grating to produce the
color phenomena. (6,000X) (See p.109.)

109

due in part to microstructural changes and to precipitation occurring during
the tests. Light and electron microscopy showed that the size of the slip
bands, precipitates, and subgrains increased with increase in test tempera-
ture and with decrease in stress.

Some data were obtained in a study to determine the influence of elevated
temperatures (up to 1200 °F) and stress systems on the tensile properties
of a titanium — 8 aluminum — 1 molybdenum — 1 vanadium alloy. Initial re-
sults indicate that the flow and fracture strengths increase with increase in
notch depth and with decrease in notch angle or root radius. Additional
research is being conducted to correlate the relations of atomistic structure
of metals to engineering properties of these metals.

Gage Block Materials Demonstrate Desired Stability. Two types
of gage blocks developed during the past few years indicated a dimensional
stability of better than 0.1 microinch per inch per year. Seven additional
types, all having a surface hardness of Rc 65 or greater, were produced
which exhibit stability of betwen 0.1 and 0.2 microinch per inch per year.
This degree of stability meets the target requirements of the project. Re-
search is continuing to further improve other properties (thermal, corrosion,
wear) and to establish performance characteristics over longer periods of
time. Studies to determine the nature and kinetics of some of the less under-
stood processes causing instability are being continued.

Deformation of Metals Studied at Low Temperatures. The effect
of multiaxial stresses induced by notches on the tensile deformation and
fracture characteristics of metals is being investigated at low temperatures.
In current work, annealed specimens of type 310 austenitic stainless steel,
a ductile metal of face-centered cubic structure, are being used. Tensile
specimens are of circular cross section and have circumferential notches of
selected geometries and depths.

Data obtained in tests at room temperature on deeply notched specimens
showed that a crack initiated in the region at the root of the notch at a rela-
tively low strain grows slowly with additional deformation of the specimen.
For example, a visible crack was initiated in a specimen at a reduction in
area value of approximately 20 percent at the notched section, even though
the reduction in area at the maximum load condition was nearly 30 per-
cent and the reduction of area at complete fracture was 55 percent.

Further studies are in progress to determine the specific effect of the
geometry of the notch on the deformation and fracture characteristics of
this steel.

Slack-Quenching Technique Developed. The best combination of
high strength and ductility of structural steels is usually obtained by com-
plete hardening and tempering. Although it is known that incomplete hard-
ening (slack quenching) with or without tempering results in an inferior
combination of strength and ductility, quantitative evaluations of its del-
eterious effect have not been possible because of lack of means for produc-
ing specimens with controlled amounts of slack-quenched structures.

110

Suitable techniques were developed during the past year, and the effect of
slack quenching upon the tensile and fatigue properties of steels is being
studied.

Stress Corrosion of Carbon Steels. In experiments with notched
specimens of four different low-carbon steels, intercrystalline stress-
corrosion cracks formed in pairs at the roots of notches in ammonium
nitrate solutions, with no evidence of hydrogen evolution. On the other
hand, single cracks formed in acetic acid-hydrogen sulfide solutions that
were primarily transcrystalline and there was evolution of hydrogen. It
is therefore not likely that hydrogen plays any part in the stress-corrosion
cracking of low-carbon steels, and that hydrogen embrittlement is an
entirely different type of phenomenon.

Effect of Applied Current on Aluminum Corrosion. Studies of
the effect of current on the corrosion of aluminum showed that continu-
ously applied cathodic currents provide cathodic protection of the metal
in neutral and acid sodium chloride solutions, but that cathodic corrosion
occurs in alkaline salt solutions.

Corrosion Reactions Studied at Metal Surfaces. Experiments on
the initial stages of the oxidation of iron at room temperature indicated
that the rate of oxidation depended on the pressure below about 10"4 torr,
but that it was pressure independent above that pressure. The increase in
thickness at the lower pressures varied linearly with time at the beginning
of the process, as predicted by the Cabrera theory.

The nature of the films formed on anodically polarized iron surfaces
was also investigated. It was found that the passive films formed in both
acidic and slightly alkaline solutions were three-dimensional compound
films rather than oxygen monolayers as stated in some theories.

Studies of the initiation of metal oxidation with the field emission micro-
scope, partially supported by the Advanced Research Projects Agency,
were continued during the year. At low oxygen pressures, the forma-
tion of nickel oxide showed a strong dependence upon the metal crystal
face.

Pure Alloys Prepared. Some projects under way at the Bureau re-
quire special alloys of high purity or with other special properties. Since
they are not available commercially, a laboratory was set up for the prepa-
ration of such materials. Typical examples of those prepared during the
year were high-purity magnetic and nonmagnetic alloys less than 325-
sieve size for nuclear magnetic resonance studies. Several series of high-
purity alloys were made for corrosion studies and special ternary alloys
of molybdenum, chromium, and nickel for other types of research.

Standard Samples. The gas-content analyses of samples of unalloyed
titanium and of an 8 percent manganese-titanium alloy were received
from cooperating laboratories and the analyses are being evaluated prior
to the issuance of the materials as standard samples. The gas content
of three other titanium alloys and of four steels is also being determined,
so that they may be made available as standard samples.

Ill

Equilibrium Diagrams Developed. NBS metallurgists, in work for
the Atomic Energy Commission, studied the metallic reactions between
uranium and the individual elements of the platinum metals by measuring
the properties of the respective alloys. The resultant data, presented in
the form of equilibrium diagrams, show the compounds formed between
two elements, the temperatures at which the metallic reactions occur, the
mutual solid solubilities, and the transformation temperatures of uranium.
The diagrams form the basis for further theoretical work on the inter-
actions of the individual metallic elements.

Experimental Alloy Demonstrates Usefulness. The superiority of
the 60 chromium— 40 nickel binary alloy over conventional iron-base alloys,
when subjected to corrosion-erosion attack in oil-fired naval boilers, was
exhibited both in laboratory tests and in actual usage on naval vessels.
Further tests showed that the resistance of the alloy can be improved by
the addition of certain elements, and by preparation under vacuum con-
ditions rather than by melting under an argon atmosphere. This work
was supported by the Navy Bureau of Ships.

Steel Pilings Inspected. Under the sponsorship of the American Iron
and Steel Institute, driven steel pilings which had been in service for from
7 to 40 years in a variety of soil conditions in the country were inspected
during the year. No appreciable corrosion was found in "undisturbed"
soils below the water table regardless of the type of soil into which the
pilings were driven. Above the water table some, but not serious, cor-
rosion was found. These results contradict those often obtained on pipes
and other materials buried in "disturbed" soils, and the reason for these
different findings is being sought.

Correlation Effects for Impurity Diffusion. Since an impurity
atom in a metal can strongly affect the vacancy jump frequencies in its
vicinity, correlations between the directions of successive atom jumps are
especially important to studies of impurity diffusion. In recent research,
detailed calculations were made to determine the effect that dissociation
and re-association of vacancy-impurity complexes has on these correlations,
and a nonzero lower limit was established. The resulting equations allow
a more detailed description of vacancy jump frequencies near an impurity.

Electron Microanalysis Provides Basic Data. The Bureau's elec-
tron probe microanalyzer, which permits quantitative chemical analyses in
situ to be made at a 1-micron level of spatial resolution, was used to investi-
gate the uniformity of elements in low-alloy standard steels. An NBS steel,
designated Standard Sample No. 461, was found to be uniform on a micro-
scale in both iron and nickel. A decomposition mechanism for columnar
grains formed by nitriding a titanium alloy was also deduced with the aid
of the microanalyzer. Theoretical work was directed at the methods used for
reducing directly obtained X-ray intensities to chemical compositions.

Quantitative Metallography Derived With Computer. A data-
processing program for the automatic quantitative analysis on micrographs
of an NBS electronic computer was completed and applied to a number of

112

research problems. In this program, 28 picture control and analysis opera-
tions are achieved by simple orders in English format. During the year,
analyses were completed on a series of color micrographs of niobium-tin
superconductor wire and on the microstructure of a steel designated Stand-
ard Sample No. 461. Work was undertaken to develop a standard for
graphite particle size in ferrous materials by means of the computer technique.
Feasibility tests were conducted on micrographs of photographic emulsions
and on biological micrographs in the fields of chromosome identification,
cancer cells, and nerve cells. The program was found generally applicable
to these types of micrographic problems as well as those in metallurgy.
Programming is in progress for a more extensive and faster system on a new
NBS computer.

Anisotropic Effects Studied in a Cubic Alloy, An investigation of
the Pb207 nuclear magnetic resonance absorption linewidth in a series of
lead-indium alloys as a function of applied magnetic field revealed a broad-
ening mechanism heretofore unobserved in alloys. This source of line broad-
ening arises because of the interaction between nuclear spins and unpaired
electron spins outside the nucleus. It vanishes when the resonant nuclei
have local cubic symmetry. The presence of this field-dependent "aniso-
tropic Knight shift" broadening is possible in the face-centered cubic phase
of the alloy because of the deviation from local cubic symmetry at the
Pb207 sites produced by adding indium atoms, and the broadening indicates
a large anisotropy in the electronic wave functions at the Fermi level in this
alloy.

X-Ray Diffraction Employed for Crystal Structure Studies. This
work is concerned with the analysis of lattice stresses as deduced from inter-
atomic layer strains, measured from X-ray diffraction data. Some results
concerning residual stresses in plastically deformed steels were published,
and a study is now in progress on coarse-grained polycrystalline samples.
Also under way is an investigation of crystal perfection by means of fine-focus
divergent beam X-ray techniques.

Dislocations in Metals Investigated. The effects due to dislocations
in metals are currently being examined from several points of view. Trans-
mission electron microscope methods are being employed to examine stack-
ing faults and twins in high-purity copper. Thermal evaporation from
cleavage surfaces of zinc single crystals was found to occur preferentially
at dislocations. The detailed shapes of the resulting evaporation pits were
studied as a function of vapor undersaturation and surface impurities.
Step configurations on the zinc surfaces were examined by electron micro-
scope replica techniques. The vapor deposition of gold on these surfaces
is also being employed to study the surface steps that are related to dis-
locations in the crystals.

Kinetics of Whisker Growth and Evaporation. In Bureau studies
of the kinetics of metal whisker growth from the vapor phase, it is assumed
that growth takes place by adsorbed atoms surface-diffusing to a sink (an
emergent screw dislocation) at the whisker tip. But the problems of de-

113

Optical interference micrograph of a thermal evaporation pit on a zinc surface.
These pits are being studied for information on the effect of dislocations on
metal behavior. (460x) (Seep. 113.)

scribing growth rate as a function of pressure, the evaporation time of
adsorbed atoms, and the surface-diffusion coefficient are complicated by
the occurrence of moving boundary conditions. Hence, an integral equa-
tion which incorporates these conditions was derived and programmed for
the Bureau's electronic computer. The resulting numerical solutions should
be useful in analyzing the experimental data thus far obtained on whisker
growth.

In work partially sponsored by the Advanced Research Projects Agency.
data on the growth and evaporation kinetics of crystal whiskers of potas-
sium and of mercury were obtained from direct optical measurements in
sealed-off vessels prepared by ultra-high-vacuum techniques. The data were
compared with theoretical estimates obtained from solutions of the surface-
diffusion equation. Over certain ranges of vapor undersaturation, crystal
edges were not found in this work to act as evaporation step sources; the
subsequent growth and evaporation of whiskers appeared to be quite sym-
metrical processes that could be well described by a single surface-diffusion
equation.

Properties of Electrode posited Copper, Electrodeposited copper
is an important material for electroforming and for other engineering ap-
plications; however, to improve and expand its usefulness in these applica-
tions, additional information is needed on the relationships between its
properties and conditions of deposition. To fill this need a new program,

114

supported jointly by the American Electroplaters' Society, the International
Copper Research Association, and the Bureau was initiated.

The microstructure of the deposits and their mechanical, electrical, and
thermal properties will be determined and related to the type of plating
bath and operating conditions. A similar study of electrodeposited nickel
completed sometime ago was found to be of considerable value to the electro-
plating industry.

Electrocrystallization Investigated, A program was initiated under
the sponsorship of the Advanced Research Projects Agency and the Harry
Diamond Laboratories to study the growth of metal crystals by electrodeposi-
tion. This method of growing crystals offers a distinct advantage over other
methods in the apparent ease by which the rate of growth may be controlled.

Polycrystalline masses, dendritic growth, and single crystal growth can
be achieved from aqueous solutions and from fused salts. This flexible
technique of growing metal crystals promises to yield significant informa-
tion of scientific interest. The initial phase demonstrated the prevalence
of growth twins in electrodeposits, and these twins appear to be related to
the growth mechanism of dendrites and of dense deposits.

Distributions of crystal orientation in polycrystal electrodeposits of copper
were determined for the first time and change in distribution accompanying
deposit growth was found. Growth of copper dendrites showed a fivefold
symmetry about the axis of growth.

Calorimetry Used To Study Fused Salts, A calorimeter, operated at
temperatures up to about 800 °C, was constructed for measuring the heat
effects involved in the formation of complex ions in fused salts. The for-
mula of a complex formed from two salts can be determined by measuring
the heat effects attending the addition of small increments of one salt to
mixtures of the salts covering the whole range of composition. The heat
effect varies with the composition of the melt. In current work, sponsored
by the Atomic Energy Commission, the complex ions formed in a mixture
of molten potassium chloride and cadmium chloride are being studied.

Peltier Effect Measured at Liquid Junctions, The flow of current
across the junction of two electrolytes — for example, 1.0 molal hydrochloric
acid in contact with 3.0 molal potassium chloride — results in either a heating
or cooling effect at the junction, depending on the direction of current flow.
This phenomenom, which is called the Peltier effect, is considered due to the
existence of a voltage at the junction, and it is measured with sensitive
thermistors. The value of the Peltier voltage is obtained by dividing the
heat effect in joules by the current in coulombs. In a recent study, sponsored
by the Atomic Energy Commission, the Peltier voltage was found to be about
80 mv for the two solutions mentioned and to be independent of the current
density, the diffuseness of the junction, or the length of time that current
was passed across the junction.

Cooperative Services Provided, Among the more interesting co-
operative services of the engineering metallurgy laboratory performed during
the year were the examination of stainless steel reflecting disks and support

115

arms for the Post Office Department (these disks are designed for attach-
ment to Post Office trucks so that drivers may view the area immediately
below the bumpers and so avoid striking small children) ; the examination,
for the Interstate Commerce Commission, of the welds from a mobile pro-
pane gas tank that exploded with considerable loss of life and property in
Berlin, N.Y. ; and the collaboration with Bureau staff in the Engineering
Mechanics Laboratory on the selection of stainless steel for large dead-weight
testing machines.

2.2.5. POLYMERS

The Bureau conducts research on natural and synthetic polymeric ma-
terials— rubber, textiles, paper, leather, and plastics — which are composed
of long, chainlike molecules. Many of the useful properties of these ma-
terials depend upon molecular size, shape, distribution, and flexibility. To
aid in the efficient utilization of polymeric materials, the Bureau investigates
the mechanisms involved in forming polymers, their constitution and mo-
lecular structure, and methods for measuring their properties. The data
obtained are of value not only in developing new materials having specific
properties, but also in devising standard techniques for evaluating those
already in use and in preparing engineering standards to promote the eco-
nomic growth of polymer industries.

Methods were reported during the year for the analysis of ethylene-
propylene rubber, determination of bitumen content of expansion-] oint fillers,
measurement of tensile properties of paper and tongue-tearing strength
of woven fabrics, identification of antioxidants in synthetic rubber, and
nondestructive examination of internal structure of composite products by
point-projection X-ray microscopy. Work was undertaken on the macro-
porous structure of leather, phase transformations in polymers at high pres-
sures, phase equilibria in polymer solutions, thermodynamic properties of
polymers, effect of pressure on the crystallization of natural rubber, and
failure behavior of fibers at high impact velocities. Chemical investiga-
tions were concerned with radiation-induced polymerization at high pres-
sures, synthesis of fluoroaromatic monomers and polymers, effects of gamma-
radiation on polymer scission and crosslinking, structure of metallo-organic
coordination polymers, production of two stereoregular forms of polyace-
naphthylene, and adsorption of polystyrene from solution onto a metal
substrate. Two standard samples of polystyrene were issued for calibration
of molecular weight measurements. In research conducted in cooperation
with the American Dental Association and Federal dental services, signifi-
cant contributions were made to knowledge of the structure and strength
of teeth, the analysis of gold alloys, and the improvement of dental cement-
ing compounds.

Ethylene-Propylene Copolymers Analyzed. Elastomers prepared
by random copolymerization of ethylene and propylene with Ziegler-Natta
type catalysts are commercially important because of the low cost of the
raw materials and the wide range of physical properties obtainable. To
achieve the elastic quality of rubber, the propylene content of the polymer

116

must be controlled within certain limits. An analytical method developed
for quantitatively determining propylene in both raw and cured copolymers
is applicable over the entire range of propylene concentrations. The method
is based on the fact that pyrolysis of ethylene-propylene copolymers pro-
duces characteristic unsaturated carbon compounds which are identified by
infrared absorption spectroscopy. It was found that the ratio of the
absorption of the vinyl groups to that of the vinylidene groups in the pyrol-
yzate varies reproducibly with the mole fraction of propylene in ethylene-
propylene copolymers.

Bitumen Content in Expansion Joint Fillers Readily Determined.
A comparison of a Soxhlet extraction method for the determination of bi-
tumen content in expansion- joint fillers (made of bitumen and cellulose
fiber, cork, or glass wool) with the current centrifuge method recommended
by the American Society for Testing and Materials, showed that the Soxhlet
procedure required less operator time and smaller amounts of solvent than
did the ASTM method. With the Soxhlet procedure it was also possible
to analyze a large number of samples concurrently with a minimum amount
of attention. A statistical analysis of the data showed that the results ob-
tained by both methods were in good agreement.

Tensile Properties of Paper. Tensile properties have long been used
as a measure of the quality of certain papers, but in recent years they have
assumed added significance in the efforts of manufacturers to develop stronger
papers for shipping sacks and similar products. An interlaboratory study
of the precision of test methods for tensile strength, stretch, and tensile
energy absorption was therefore undertaken at the request of the Technical
Association of the Pulp and Paper Industry to improve the precision of the
measurement system. Twenty laboratories participated in the testing of 22
materials.

The results showed that a standard reference material would be of little
or no value for standardizing the tests for tensile breaking strength and
tensile energy absorption, although it might improve the precision of the
stretch method used. The 95 percent probability limits for the differences
between the averages for two sets of 12 measurements by each method were
found for tests of the same material by a single observer, for tests of different
materials measured under the same conditions, and for results obtained by
different observers or instruments.

Tongue-Tear Methods for Woven Fabrics Evaluated. The tongue-
tear (or "single-rip") method is widely used in measuring the strength of
woven fabrics, but five different procedures have been standardized and
published for this test. The Textiles Committee of the American Society
for Testing and Materials therefore requested the Bureau to undertake a
study of their relative precision. Thirty laboratories collaborated in the
project, which was conducted by the Mandel-Lashof statistical plan with
eight different materials.

The results showed that two of the procedures in which a constant-rate-
of -elongation testing machine is used are better than the other three. In

117

one of the superior procedures, the result from an integrator average is
computed and, in the other, an average of five peaks in the autographic-
record of the tearing load is used. The results also showed that five repli-
cate determinations are needed for routine measurements and ten for inter-
laboratory measurements, and that a standard reference material would be of
little value in improving the precision of measurement. Estimates were made
of the precision of the five procedures for use in ASTM precision statements.

Color Tests Devised for Antioxidants in Synthetic Rubbers, A
scheme of color tests was developed for identifying the five antioxidants com-
monly used in styrene-butadiene synthetic rubbers. These antioxidants in-
clude naphthylamine and diphenylamine compounds, styrenated phenols, and
alkylated arylphosphites. By the use of specified successive tests involving
two or more of a group of twelve reagents, the uncertainty of distinguishing
between similar colors obtained with a single test is overcome. The pro-
cedure also permits the detection of small amounts of staining antioxidants,
which might be present as contaminants.

Point-Projection X-Ray Microscopy Used To Study Polymers.
Microradiography, a technique using soft X-rays generated by point-
projection sources, is being applied to the examination of a wide range
of polymeric materials. Because of its high resolution (greater than most
light microscopes) and its ability to image opaque and thick specimens,
this technique provides a powerful tool for polymer research. Studies
were made on foams of polystyrene, polyurethane, vinyl, and other ma-
terials, to characterize cell structure and to correlate structural anisotropy
with physical properties.

Point-projection microradiography is being applied to the study of polymers.
This high-resolution technique can be used on opaque and thick specimens.
Left: microradiograph of chemically modified polyurethane foam; right:
fully expanded polystyrene beads. (See p. 118.)

118

In studies of paper formation, the method permitted detailed study of
the size and location of fillers and additives. In addition, the condition
and form of adhesives and reinforcing components in polymeric materials
could be easily imaged by the method. The point-projection source also
provides an efficient means of producing divergent-beam (Kossel) diffrac-
tion, which permits detailed analysis of the structure of crystalline monomers
and of the changes occurring during solid-state polymerization.

Leather Macroporous Structure Investigated. The pore structures
in leather and other natural collagenous materials, and in plastics and
fritted glass disks were compared with a mercury porosimeter at absolute
pressures ranging from 5 to 3000 psi. Pore radii corresponding to these
pressures are in the macropore range from 50 to 0.04 microns (/*). The
results demonstrated that many different pore sizes exist in the fibrous
structure of leather, whereas the pores in manufactured materials are
more uniform in size.

A differential analysis of integral volume-pressure curves derived for
collagenous materials in the form of hides indicated that a large part of
the pore volume occurs at radii of from 5 to 0.5 fx. In rattail tendons, a large
fraction is in the 2.5- to 0.5-/U radius range. The volume from pores
smaller than 0.25-/X radius is probably within the fibril region of the
collagenous materials.

Structural Transformations Observed in Polymers at High Pres-
sures. Physical changes under high pressure were observed in a variety
of polymers compressed between diamond anvils at room temperature. The
diamonds serve both as load-bearing surfaces for pressures up to 70 kilo-
bars and as light transmitting media. The anvil device is placed on the
stage of a polarizing microscope to increase resolution.

In the study, the optical appearance of some polymers (e.g., Teflon, Kel-F,
and nylon 6) changed abruptly during compression. The original field,
which showed little structure with shifting interference colors associated
with increasing photoelastic strain, was changed to a reticulated structure
with low birefringence. The transition point was usually marked by a
snapping noise. Other polymers (natural rubber, polyisobutylene, and
ethylene-propylene rubber) showed a more gradual transformation in which
internal grooves developed and spread throughout the field with increased
pressure until a reticulated structure resulted.

The transformations were irreversible, at least on a time scale of several
months. X-ray diffraction patterns of compressed rubbers after removal
from the anvil device showed crystalline rings which were not previously
present. Polyethylene displayed a new spacing associated with a psuedo-
triclinic unit cell. Polymers that transformed abruptly had a polymer glass
transition temperature (T0) above room temperature; those that trans-
formed gradually had a Tg below room temperature.

Phase Equilibria in Polymer Solutions. Light-scattering studies of
polystyrene-cyclohexane solutions near their maximum phase separation tem-
perature showed differences in the distribution of molecular weights that

714-691 O — 64-

119

could not be easily determined by other physical chemical methods. The
light scattered in the direction of the incoming beam was determined by
measurement of the light scattered to the side and extrapolation to the for-
ward direction. At a given temperature the scattering was measured as a
function of concentration over a concentration range of from 1 to 10 percent.
The temperatures varied from a few hundredths to a few tenths of a degree
from the critical temperature.

The shape oj the resulting isotherms and the shift of the maximum indi-
cated the polydispersity of the sample. The measurements obtained consti-
tute a sensitive test for the existence of true monodispersity in a polymer.
They also lead to a direct experimental determination of the thermodynamic
properties of concentrated polymer solutions. The results show that current
theory of phase equilibria in polymer systems does not satisfactorily fit experi-
mental data, since it does not include concentration-dependent interaction
terms in the critical region.

Statistical Calculations Made of Polymer Properties. Thermo-
dynamic properties of polymer chains were calculated on a statistical basis
in a recent Bureau study. Nonbonded nearest-neighbor, next-to-nearest-
neighbor, and other interactions were counted, and, by introducing an
appropriate potential energy of interaction between the neighbors, various
thermodynamic properties could be derived. Attractive forces between
neighbors led to very compact (supercoiled) conformations resembling
tightly packed spheres. However, repulsive forces extending over a reason-
ably large range of intramolecular separations led to rodlike polymer
conformations.

Computations were made of the free energy and of the entropy per link of
polymer, with respect to a preselected reference state. This state corresponds
to a conformationally unrestricted polymer coil. Variations in the thermo-
dynamic properties of a polymer as it undergoes conformational changes
could thus be derived. From such calculations it was concluded that the
thermodynamic properties of polymers do not vary markedly with molecular
dimensions. Even in a very good solvent, in which polymer-solvent contacts
are favored over polymer-polymer contacts, polymer chains tend to remain
in relatively coiled conformations.

Rubber Crystallization Investigated. The crystallization of purified
natural rubber was investigated by observing the change in volume at tem-
peratures from +10 to —30 °C under hydrostatic pressures up to 800
kg/cm2. Superimposable Avrami type isotherms were found at all tempera-
tures and pressures. A study was made of the effects of temperature and
pressure on the critical free energy necessary to form a nucleus and on the
activation free energy required for transport across a liquid-nucleus inter-
face. It was found that the data could be quantitatively explained by means
of a simple assumption that the activation free energy for transport was
independent of the temperature.

Failure Phenomena of Fibers Studied at High Impact Velocities.
When a filament is struck transversely, a V-shaped wave of transverse motion

120

Multiple microflash photograph of a textile yarn being broken by a rifle bullet.
This method is used to study the behavior of textiles under high impact forces.
(Seep. 120.)

spreads outward at a velocity that depends upon the velocity of impact.
Data on the wave velocities, corresponding to impact velocities between
10 and 700 meters per second (m/sec), can be analyzed to determine stress-
strain behavior at straining rates of the order of 100,000 m/sec. In recent
experiments, textile yarns were impacted with rifle bullets and a multiple
exposure of the resulting configurations was obtained by means of micro-
flash photography. The flash apparatus emitted a series of 15 flashes of
1 -microsecond (^sec) duration separated by time intervals as short as 10
fisec.

121

It was found that the time required to break a yarn depended upon the
impact velocity. For example, a high-tenacity polyethylene terephthalate
yarn broke 10 /usee after impact at 620 m/sec, but required 100 fisec to
break after an impact at a velocity of 420 m/sec. Similar relationships
existed between impact velocity and the breaking tenacities and elonga-
tions of the specimens. Information of this type is sought since it gives
a better understanding of the mechanical properties of polymers and their
dependence upon molecular structure.

Radiation-Induced Polymerization Under High Pressure, To de-
termine the influence of pressure on polymerization and to produce poly-
mers of unusual or novel structure, studies are under way in which monomers
that are nonpolymerizable under ordinary conditions are subjected to pres-
sures near 20,000 atm and irradiated at 25 to 300 °C with gamma-rays.

Placing a monomer sample into a cobalt 60 radiation source 10 feet under
water (lower center). Under the influence of the gamma radiation, high
pressures, and high temperatures, several monomers which do not ordinarily
form polymers have been polymerized. Polymers of unusual or novel struc-
ture with unique properties may be produced by such studies. (See p. 122.)

122

Monomers thus far polymerized in this investigation, sponsored by the U.S.
Army Research Office, included perfluoroheptene, carbon disulfide, 4-chloro-
perfluoroheptadiene-l,6,perfluoropentadiene-l,4, and perfluorocyclobutene.
The results showed that the rate of polymerization is usually proportional
to the square root of the irradiation intensity. In several instances, poly-
mers of promising physical properties and molecular weights were obtained.
Equipment is being developed to conduct the polymerization at still greater
pressures.

Fluor oar omatic Polymers Prepared. An intensive study of the
chemical synthesis of new perfluoroaromatic monomers is being carried out
under the sponsorship of the Bureau of Naval Weapons, with the objective
of producing elastomers resistant to high temperatures. In this research,
perfluorophenylene ethers were prepared from pentafluorophenol and its
salts. The highest molecular weight polymer obtained exhibited interesting
properties up to approximately 400 °C, the decomposition temperature of
the material.

Perfluorovinylphenyl ether was also prepared and polymerized to low
molecular weight polymers.

It is anticipated that perfluorophenylene methylene polvmers would have
outstanding thermal stability. As a precursor to the synthesis of this poly-
mer, p-hydro-perfluorotoluene was prepared, and its ability to undergo
anionic and cationic reactions was studied in a search for an efficient poly-
merization process.

High-Energy Radiation Effects on Polymers. A study of the
changes induced in the physical properties of polymers by a high-energy
radiation environment was undertaken for the National Aeronautics and
Space Administration. Such information is needed to advance both space
and nuclear technology. The results showed that the properties of an
elastomer change drastically when it is irradiated. The radiation induces
a series of complex chemical changes which lead to broken polymer chains
and to crosslinking, with both processes usually occurring simultaneously.

In the investigation, stress relaxation resulting from the rupture of polymer
chains was recorded for fluoroelastomers in a gamma-ray source. It was
found that the dose required for 50 percent stress relaxation in a copolymer
of vinylidene fluoride and hexafluoropropylene was 12 megarads (Mrad) in
the absence of air and 6 Mrad in air, at a dose rate of 0-3 Mrad/hr. Similar
findings were made on other fluoroelastomers. A rather large component
of rupture was observed in the overall crosslinking of these polymers upon
irradiation.

The rates of volatilization of polymers were recorded automatically while
they were heated in a gamma-radiation field. A greatly enhanced rate of
volatilization of polytetrafluoroethylene occurred at temperatures from 300
to 400 °C, far below the 500 °C temperature at which ordinary thermal de-
composition becomes appreciable. Elucidation of the mechanism and ther-
modynamics of the radiation-induced degradation process is necessary be-
fore polymers suitable for use in radiation fields can be synthesized.

123

Thermal Stability of Coordination Polymers Investigated. In re-
cent research, the thermal stability of coordination polymers of bis (8-
hydroxy-quinoline ) derivatives heated in vacuum was related to the metal
atoms that linked the organic units (ligands) in the polymer chain. The de-
composition temperatures of polymers containing either divalent manganese,
cobalt, nickel, or copper decreased linearly from approximately 510 to 420
°C with increasing atomic number of the metal. A divalent zinc polymer,
being more stable than the copper polymer, showed an interesting departure
from this trend.

It was demonstrated that the mechanism of decomposition involved
cleavage of the metal-ligand bonds at the coordination site and that the
order of stability depended on such periodic properties of the metal as
ionic potential and electronegativity. These findings may make it possible
to predict the thermal stability of other coordinated systems and they may
suggest structures for polymers of greater heat resistance.

Stereoregular Polyacenaphthylene Produced. A recent advance in
polymer chemistry is the ability to synthesize stereoregular polymers by
the use of special catalysts. Another approach to the preparation of these
regular structures is through the use of monomers of high steric hindrance.
The polymers formed from such monomers are expected to have stereo-
regularity due to crowding of the bulky side groups.

Since acenaphthylene has a very large group bridging the polymerizable
vinyl group, the polymer formed from it should exhibit the extreme effects
of steric hindrance, both in its polymerization kinetics and in its physical
and chemical properties. The polymerization should occur in either a
syndiotactic "rodlike" form or an isotactic, tightly coiled helix. Meticulous
separation of the products of ionically initiated polymerization and charac-
terization by infrared and nuclear magnetic resonance spectra show that
both structures do in fact exist in polyacenaphthylene.

Polymer Adsorption. Polystyrene films adsorbed from cyclohexane
on chrome surfaces were recently studied in work partly sponsored by the
Bureau of Naval Weapons. Purpose of the study was to obtain a better
understanding of the nature of the interface between glass fiber and polymer
in reinforced plastics. In the study, ellipsometry was used to measure
changes in the state of polarization of polarized light reflected from the
film-covered surface. From these measurements, the thickness of the film
was calculated to be about 200 A. The film consisted of about 12g/100 ml
of polymer and the amount adsorbed was determined to be approximately
2.25 X 10-4 mg/cm2.

Molecular Weight Standards for Polystyrene. Research to improve
precision and accuracy of measurements of polymer molecular weights,
particularly by osmometry, light scattering, and ultracentrifugation, has
culminated in the issuance of two standard samples of polystyrene for calibra-
tion purposes. These materials, the first molecular weight standards for
polymers to be made available by the Bureau, will be of value to chemists
in the characterization of industrial macromolecular produjts used in the

124

manufacture of plastics, rubbers, textiles, and paper. Molecular weight
and intrinsic viscosity are given for each sample. Each sample is also charac-
terized for ash content, volatile content, and refractive index increment and
partial specific volume constants of the polystyrene-cyclohexane solutions
used in light scattering and sedimentation molecular weight determinations.
Structure and Strength of Teeth. Electron microscope examination
of developing enamel showed that mineralization begins by the formation
of extremely thin ribbons of calcium phosphate which subsequently thicken
to become fibrous crystals of hydroxyapatite, Ca5(P04)3OH. In coopera-
tion with the National Institute of Dental Research, the crystallographic and
chemical evidence concerning the nature of the ribbons was reexamined
with the conclusion that octacalcium phosphate, Ca4H(P04)3*2.5H20, is a
better prototype for the ribbons than the presently accepted hydroxyapatite.
These two salts differ greatly in their chemical properties, so that a distinc-
tion as to which salt comprises the ribbons is needed for an understanding, on
the molecular level, of the calcification mechanism. For example, the pres-
ence of fluoride during the enamel formative state has pronounced influence
on subsequent caries development. Fluoride is known to cause octacalcium
phosphate to hydrolyze to the less soluble fluorapatite.

Dental calculus (tartar) consists of about 20 percent organic material
in a matrix of calcium salts, mainly phosphates. Studies were undertaken
to determine the composition of the organic portion for possible assistance
in the search for agents that might reduce the formation of calculus. Or-
ganic layers at the junction of the calculus deposit and tooth tissue and
throughout the deposit were demonstrated by their fluorescence. Chromat-
ographic and electrophoretic analyses showed the presence of a mucoprotein
(a carbohydrate-protein complex), indicating a possible role of salivary
mucoid in the formation of dental calculus.

The small size of specimens that can be prepared from human teeth requires
special techiques for measuring the tensile strength of enamel and dentin.
Hence, a method was developed that employs a dumbbell type specimen of
0.0015-in.2 cross section, with notched ends embedded in resin. The resin
ends fit into grips attached to the testing machine. The dentin specimens
were long enough to permit attachment of %-in. strain gages for modulus
determination. The tensile strengths of human enamel and dentin stressed
at a head speed of 0.002 in./min were 1500 and 7500 psi, respectively. The
modulus of elasticity of dentin was found to be 2.8 X 106 psi.

The studies in this program were sponsored by the American Dental As-
sociation and the Federal dental services.

X-Ray Spectrometer Used for Analysis of Dental Alloys. Stand-
ard reference samples were recently prepared for X-ray spectrometric anal-
ysis by melting the component elements — gold, platinum, palladium, silver,
copper, and zinc — of a dental alloy in a high-frequency furnace and cast-
ing the alloy into disks. Compositions of the castings were subsequently
checked by chemical methods. Optimum procedures for casting the sample
and for X-ray analysis were established. Analytical curves were developed

125

relating concentrations to measured intensity of the X-ray lines Au Lp, Ag
Ka, Cu Ka, Pt La, Pd K a, and Zn Ka. The procedure is more rapid than wet
chemical methods and the results appear to be sufficiently accurate for general
purpose work. The American Dental Association and the Federal dental
services sponsored this study.

Dental Cements. In other work for the same sponsors, it was found
that partial substitution of o-ethoxybenzoic acid (EBA) for eugenol as a
chelating agent results in the formation of improved dental cements. A
typical cement is obtained by mixing powder containing zinc oxide, heat-
treated fused quartz, and hydrogenated rosin with EBA-eugenol liquid. The
resulting product has compressive, tensile, and shear strengths that are about
three times those of presently available zinc oxide-eugenol cements. Solu-
bility and disintegration as measured by various laboratory tests are equal
to or better than those of zinc oxide-eugenol cements. The cement also shows
reduced setting contraction and water sorption.

2.3. SPECIAL TECHNICAL SERVICE

PROGRAMS

2.3.1. APPLIED MATHEMATICS

The Bureau's applied mathematics facility performs basic and applied
research and provides advisory services on the application of mathematical
and statistical techniques. Its services are available to other Government
agencies as well as to the Bureau's staff. The facility uses modern com-
puting equipment in support of its program.

During the past year the Bureau continued research in statistical and
numerical analysis, mathematical physics, and operations research, all of
which are fundamental to its mission. Extensive assistance was rendered
in these areas and in digital computation. In the latter field, emphasis
was placed on problem formulation and analysis in order to select and
develop appropriate numerical methods. Automatic high-speed computing
machines were utilized when appropriate. The mathematical program was
devoted both to problems in engineering and the physical sciences and to
government problems of business management and operation, sometimes
called data processing problems. Progress was continued in exploration of
the use of modern digital computers in the mechanical translation of scien-
tific publications, for which the need is urgent.

The Bureau's applied mathematics program was strengthened by the active
interest and support of other Government agencies. The Office of Naval
Research and the National Aeronautics and Space Administration supported
basic and applied research in numerical analysis and mathematical physics.
The study of mechanical translation of scientific publications was jointly
supported by the U.S. Army Signal Corps and the U.S. Army Research Office.

Numerical Analysis. Research in numerical analysis is of vital im-
portance in contributing to the effective use of electronic digital computing

126

equipment, both in applying such equipment to scientific and engineering
problems and in utilizing it as an aid to decision making by management.

If an asymptotic series is truncated at (or near) its smallest term, the
resulting partial sum is often a good approximation to the wanted function
f(x), particularly for large values of x. Because of this property, these
series are frequently used in computations, even though they are really
divergent. Only a few scattered special results are known concerning the
precise magnitude of the error committed by approximating a given function
by a partial sum of its asymptotic series.

Current research is directed toward filling this gap. Considerable success
has already been achieved with certain types of asymptotic series originating
from second-order ordinary differential equations; some general theorems
have been established giving precise, and realistic, error bounds which are
easily evaluated. The theorems also show, for example, why these series
provide inaccurate results near the boundaries of their regions of validity
in the complex #-plane.

Asymptotic Expansions. Work continued on the determination of error
bounds for the asymptotic solution in terms of Airy functions of second-
order ordinary linear differential equations in regions containing a turn-
ing point, and on the determination of complete asymptotic expansions of
such solutions.

Quadrature and Interpolation. The question of the existence and
uniqueness of functions satisfying a given set of conditions was investigated.
The use of equidistributed sequences in Monte Carlo quadrature was
investigated, both theoretically and experimentally.

Numerical experiments were conducted on the computation of highly
multiple integrals — more specifically, on the calculation of the fourth and
fifth virial coefficients of an imperfect gas — utilizing a fairly arbitrary inter-
action potential. Despite much activity on this problem over the past five
years, treatment of its numerical aspects remains unsatisfactory.

Linear Algebra and Matrix Theory. Bounds for the arithmetic minima
of quadratic forms were determined and the structure of classes of copositive
and positive quadratic forms was investigated. Theorems were given rela-
tive to the iterative solution of eigenvalue problems and to the iterative in-
version of a matrix. Such problems are of central importance in a wide
range of investigations extending from flutter of airplane wings and critical
speeds to nuclear theory.

Machine Translation. The morphological phase of the problem of
mechanical transfation of Russian into English has been entirely completed.
Theoretically, the syntactic integration phase can never be completed; but
enough progress has been made to indicate the soundness of the "predictive
analysis" scheme initiated at the Bureau. Coding for the section dealing
with the mechanical determination of the clause and phrase boundaries within
a sentence is progressing. As soon as it is completed, an open test of the
method will be made on Russian sentences composed of words formed from
the limited number of stems presently stored in the machine's glossary-

127

Mathematical Tables. In response to demand. Applied Mathematics
Series 27, Tables of 10*, and AMS 36, Tables of Circular and Hyperbolic
Sines and Cosines for Radian Arguments, were reissued. Underway is a
critical survey of all the Bureau tables series in view of the approaching
completion of the Handbook of Mathematical Functions.

Digital Computations. The Bureau improved its computational facili-
ties by replacing the IBM 1401 with an IBM 1410 computer. The 1410 com-
puter is actually rented by the Harry Diamond Laboratories, U.S. Army,
but is operated by the Bureau. In addition, the Bureau continues to operate
an IBM 7090 and plans shortly to replace this with an IBM 7094. Both
scientific and data processing problems continue to require extensive use of
these computational facilities. In addition to performing computations on
its own equipment, the Bureau assists other Government agencies in setting
up problems for other computing machines. The experience gained in
the performance of this service stimulated research in programming and
computational methods.

About one-third of the computing services tasks performed during the
year originated within the Bureau. The remainder were performed in
assistance to such agencies as the Harry Diamond Laboratories, National
Aeronautics and Space Administration, Bureau of Public Roads, Secret
Service, Treasury Department, Veterans Administration, Peace Corps, U.S.
Military Academy, and the Office of Civil Defense. Important computations
were performed on problems in the thermal dissociation of diatomic mole-
cules, diffusion and reactions in gases, polymers, multilayer adsorption
studies, neutron cross sections, equations of state, and interaction radiation.

Among the many problems in the area of data processing where the
economic desirability of supporting the development of Mach 2 to 3 super-
sonic aircraft, the comparison of different tax proposals, the analysis of
check forgeries, the evaluation of applicants for the Peace Corps, the analysis
of highway and traffic problems, and a comparison of securities marketing
procedures.

Extensive research continued in the field of automatic programming and
artificial programmer-oriented computer languages. A monitoring sys-
tem which previously utilized the 1401 computer as a secretary for the
7090 computer was adopted and enlarged for the 1410 computer.

Statistical Engineering. The principal function of the Bureau's sta-
tistical engineering program is to advise the Bureau's scientific and technical
personnel on the application of modern probability and statistical methods
to physical science and engineering experimentation. The aim of the pro-
gram is to help the Bureau's scientists and technicians conduct their re-
search, development, and testing programs so as to reach conclusions of
desired scope and reliability at the lowest possible cost under existing limita-
tions of funds, equipment, materials, and personnel. Extensive services
were rendered, ranging from short informal conferences to active collabora-
tion with project leaders for periods of several months.

128

Research and Development. Two Bureau publications completed
during the past year make available to the technical public many important
results of the Bureau's research and experience in the adaptation and de-
velopment of statistical methodology for application to calibration and ex-
perimental programs in the physical sciences and engineering. The first
of these, "Realistic Evaluation of the Precision and Accuracy of Instru-
ment Calibration Systems," J. Res. NBS 67C, No. 2, 161-187 (Apr.-June
1963) is a very thorough treatment of the principles of probability and
statistics that are fundamental to the description and evaluation of the
sources of errors in a measurement process. The paper derives from these
principles the appropriate techniques for assigning numerical bounds to the
uncertainties of measurement results.

The second publication completed last year, Experimental Statistics (to be
issued as NBS Handbook 91), was prepared under a contract with the
former Office of Ordnance Research (now Army Research Office — Durham) .
Although originally developed with the needs of the Army in mind, it should
be equally useful to other groups concerned with research and development,
both within and outside the Government. The Handbook is intended
chiefly for use by persons with an engineering background as a guide and
ready reference on the planning and interpretation of experiments and tests
relating to engineering design and development programs. Model work
sheets and examples corresponding to the more common applications of sta-
tistics are provided.

The Bureau conducts a continuing program of basic research in prob-
ability and mathematical statistics to maintain and increase the effectiveness
of statistical services. During the past year, a study of a new rank sum test
for outliers was completed, and an algorithm was developed for obtaining
an orthogonal set of individual degrees of freedom for error.

Research was continued on applications of probability theory to problems
of the reliability of complex systems. A mathematical study was made of the
reliability of a system with spare parts, where the spare parts can fail in
storage as well as in use. An investigation was initiated of mathematical
models for the description of changes through time in the probability dis-
tributions of characteristics of electronic devices. The dependence of these
distributions on age and stress level was considered.

Experiment Resign and Consultation. Major cooperative activities were
in connection with the Bureau's calibration programs. Methods for repre-
senting the precision and accuracy of measurement processess and statistical
designs for eliminating the effect of environmental factors are the subject of
most of the consulting activities.

A good example of this collaborative activity has been the work for the
Mass and Volume Section. In the calibration of a set of weights, different
combinations of the weights are compared in such a way that a value for
all the unknown weights is obtained. Such a schedule of weighing, called
a weighing design, has redundancy in the sense that more observations are
made than there are unknowns in order that there be a check on the precision
of the measurements. New weighing designs have been created which incor-

129

porate a standard weight as an unknown as a check on accuracy. A program
was provided for electronic computation of the results; this method greatly
simplifies the maintenance of records on the accuracy and precision of the
measurement process.

Mathematical Physics. Research in this area continued to be directed
toward the application of mathematical techniques to the solution of problems
in mathematical physics and the engineering sciences. Investigations in-
cluded a combined theoretical and experimental study of the laws governing
the nonlinear deformation of viscoelastic materials; the application of the
"stroboscopic" method to the study of nonlinear ordinary differential equa-
tions arising from vibration, acoustical, and electrical circuit problems; the
determination of bounds on solutions of problems involving elliptic operators,
especially those of elasticity; research on the kinetic equations governing
various plasma flows; and a study of the feasibility of measuring the
atmospheric drag on a manned satellite by means of controls to be operated
by the astronaut.

Plasma Research. Research was performed on basic problems in the
physics of ionized gases, particularly on the dynamics of motion in the pres-
ence of magnetic and electric fields. This work is essential in supporting
the basic research of the Bureau and is also important to the National Aero-
nautics and Space Administration. Emphasized were investigations of thp
interaction of solar corpuscular radiation and the magnetic field of the earth
and of dynamic phenomena, which may affect the operation of plasma pro-
pulsion devices. In particular, the kinetic equation was subjected to detailed
study, as was the structure of the correlation function and its application to
plasma oscillations.

Theory of Satellite Orbits. Analysis of the drag-free motion of an
artificial satellite on the basis of a theory developed at the Bureau was
continued. Through the use of oblate spheroidal coordinates, it is possible
to give an analytical representation of the gravitational field of an oblate
planet, such as the earth, which is nearer the empirically accepted representa-
tion than any given previously. This permits a discussion of the motion of
a satellite in terms somewhat different from those hitherto used. A so-called
reference orbit was first established, and current work is concerned with
the study of perturbations of this orbit produced by deviations from true
oblateness, such as equatorial asymmetry and oblateness of the earth.

Operations Research. General areas of investigation during the past
year included game theory, graph theory, weapon system simulation. Boolean
functions, and mathematical models of distribution networks.

Significant progress continued on studying methods for finding maxi-
mum matchings (isolated sets of edges) in linear graphs and on extending
the results to maximum degree-constrained subgraphs. The difficulty of
the algorithms increased only algebraically (rather than exponentially)
with the size of the graph. The convex hull of the incidence vectors de-
scribing the matchings of a graph was determined. This result is unusual
in that it is not the one suggested directly by the combinatorial problem.

130

Work continued on surface imbedding of graphs, leading to an abstract
characterization of surface duality, and a classification of planar imbeddings.

A long-range study of mathematical models of distribution networks
continued, with a view to optimizing the locations of sorting centers and the
degree of system centralization. A number of mathematical topics relating
to the "warehouse problem" (optimal location of a single processing fa-
cility) were identified and explored. Investigations dealing with the (some-
times surprising) effects of buffer capacities in simple flow networks were
initiated. Simulation studies of two distribution subsystems were carried
out.

Other major activities included continuation of the analysis and simpli-
fication of Boolean functions (important in network circuit theory) and
the analysis and simulation of missile system operation. In addition, de-
mand for consulting and advisory services in operations research continued
to increase.

New Computer Facilities at Boulder Laboratories. The mathe-
matics group at the Boulder Laboratories took a significant step with the
installation of a new 7090-1400 computer system. Even with the increased
capacity of the larger and more efficient system, however, the workload
has grown beyond the capability of single-shift operation. This was due
in part to the greater use being made of automatic data processing by
the Bureau's scientific and administrative staffs, and also to the extensive
use of the Bureau's computation facility by other Government agencies.
These include the Bureau of Reclamation, the Geological Survey (both of
the Department of the Interior) , and the Department of Agriculture.

Mathematics Group at Boulder Laboratories, The increased com-
putational capability obtained with the new computer system made possible
many studies by the Consultant in Mathematical Physics. These include
such studies as those of two-phase liquid flow in a pipe, Fourier coefficients
relative to attenuation measurements, and complex argument error function
for computation to high precisions.

Computational analysis programs included development of a scientist-
oriented computer-programming method called BOUMAC, which is in-
tended to minimize programming required for certain computations. Other
projects are typified by programming computation of inverse thermodynamic
functions, computing constants for measuring network voltage insertion
ratios, and an information-retrieval project conducted for the Cryogenics
Data Center at the Boulder Laboratories.

Statistical Studies at Boulder Laboratories. Work in the field of
statistics advanced programs dealing with optimum estimation of param-
eters of negative exponential distribution, the distribution of a Student's t
statistic, estimating means and mediums, approximating distribution func-
tions, and estimating parameters restricted to an interval. Applications of
probability theory were made in deriving families of power distributions
of received radio signals, analyzing variance in estimating precision of
frequency standards, modeling personnel promotions stochastically, and esti-
mating parameters of Poisson distributions.

131

2.3.2. DATA-PROCESSING SYSTEMS

The Data Processing Systems Division assists other Government agencies
to use their data-processing facilities most effectively by serving as a central
research activity for data processing within the Government. It works
as a technical consultant to, and collaborator with, other agencies in plan-
ning and implementing improvements in automated handling of both numer-
ical and nonnumerical information. To maintain its consultative facility,
paralleling the growing use in Government of data-processing equipment,
the Division must increase the competence of its staff and the versatility of
its research facilities.

In providing interagency assistance, the Data Processing Systems Division
engages in research and development involving the techniques of several
scientific disciplines. Present activities include exploration of new com-
ponents to determine their suitability for computer circuitry; studies of the
properties of materials; development of techniques for extending auto-
matic data processing in such areas as the processing of scientific infor-
mation; investigation of design procedures for assembling components into
prototype equipments and systems; exploration of the application of com-
munication science to data processing and control systems; automatic ac-
quisition and processing of data for the physical and behavioral sciences
by integrating the characteristics of the human operator with those of the
equipment; application of automatic data-processing techniques to decision-
making functions and technical supporting services in the Government;
and the operation of a center providing information on research and de-
velopment in the fields of storage and retrieval of scientific information.

More effective utilization of the many types of ADP (automatic data
processing) systems now in use or expected to be used by the Government
depends on establishment of appropriate standards, especially of input to
and output from systems. Considerable planning and effort were devoted
to such standardization through both intragovernment and Government-
industry cooperation. The Data Processing Systems Division participated
in the standardization panel of the Bureau of the Budget's ADP Advisory
Council and maintains an active staff member on the American Standards
Association's Sectional Committee X3 — Computers and Information Proc-
essing and its many subcommittees and task groups. The establishment
of the American Code for Information Interchange (a 7-bit code) encouraged
the Bureau to investigate means for converting data produced in different
formats into the standard format.

Research Information Center, The Research Information Center and
Advisory Service on Information Processing, sponsored jointly by the
Bureau and the National Science Foundation, continued to collect and orga-
nize literature and bibliographic references covering a wide range of interests
in information storage, selection, and retrieval. The collection of references
to the available literature now numbers over 12,500 items. Collecting in-
formation on current and proposed research projects and identifying the

132

research workers in. the field have been continued in order to provide such
information when requested by personnel in Government and industry.

Preliminary indexing vocabularies have been set up for selected subsets
of documents and the work of abstracting, indexing, and establishing subject
control of the pertinent literature has continued. The first 35 items of the
pattern recognition subset have been microfilmed and are now ready for
experimental subject searches on the rapid selector. Descriptive cataloging
rules and coding requirements for all items in the collection have been
formalized for full compatibility with multipurpose machine processing.

The Research Information Center issued a state-of-the-art report composed
of a bibliography of foreign developments in machine translation and in-
formation processing. Two preliminary manuscripts on automated com-
puting techniques for literature announcement media and on paper-scanning
and paper-handling techniques for use with film optical sensing devices are
being edited.

A continuing literature search and survey of existing equipment and de-
velopments for printed character recognition, speech recognition, and code
recognition is being conducted under the sponsorship of the Army Signal
Supply Agency. An ancillary study deals with the special problems associ-
ated with recognition of Chinese characters; a possible approach is by arrang-
ing each character in certain topological relationships. The center is con-
tinuing to provide bibliographic and other services to cooperating workers
in the field, to Government agencies, and to interested correspondents.

Components and Techniques, The study of new and existing com-
ponents continued as basic to developing economical, higher speed, more relia-
ble, efficient digital data-processing devices having lower power requirements.
The importance in a system of the capability of producing fast rises and
of measuring and resolving extremely short durations (e.g., one nanosecond)
led to the study of ultrathin ferromagnetic films as potential high-speed ran-
dom access memory elements. This in turn involved studies of a strip
transmission line for producing drive fields and a sampling oscilloscope for
measuring switching signals.

The technique of quantitative analysis of thin films by X-ray fluorescence
also was studied. A new hysteresis loop tracer was designed and constructed
for measuring the dispersion of the anisotropy axis in films. In this con-
nection a study was made of the electronic integration methods used in
making these measurements. Preliminary results indicate that the fidelity of
the hysteresis loop presentation is significantly improved by a phase-com-
pensation circuit in the integrator.

The characteristics of semiconductor devices, such as tunnel diodes and
mesa, microalloy diffused, and epitaxial transistors, were studied by use of
simulation techniques. A charge control model of a junction transistor was
simulated on an analog computer to determine the best way of driving a
switching transistor. The use of tunnel diodes and transistors was surveyed
for very fast logic circuits. A counter circuit capable of counting up to 80
megapulses was developed, based on an 80-Mc/s triggerable flip-flop multi-
vibrator incorporating tunnel diode— transistor circuitry.

133

In studying semiconductors and storage devices for memory and logi-
cal functions in computers and control circuits, the binary computer net
was reappraised and the general computer requirements described mathe-
matically in terms of digital repeater transfer functions. The description,
considerably extended and refined, does not specify physical form or logical
organization; this offers the prospect of comparing and evaluating, in com-
mon terms, computer nets differing widely in physical and logical aspects.

Scientific Information Processing. The development of a program-
ming system for processing information-retrieval prescriptions, directed at
information sources consisting of interrelated pictures and text, was con-
tinued under the sponsorship of the Patent Office and the National Science
Foundation. A prototype system accepting English sentences which de-
scribe pictures of simple geometrical shapes was developed; it directed
manipulation of the sentences and pictures to determine which sentences
were correct descriptions of which pictures. This program used a general-
purpose syntactical analyzer for phrase structure grammars, written for
the 7090 computer. A machine grammar written for the relevant fragment
of English was used as the basis for others, including larger fragments
of English. A set of programs for anlysis of simple pictures was constructed
in STRIP (a machine language developed for the SEAC). Finally, an
algorithm was written for translation of analyzed sentences into a logical
calculus.

Logical and mathematical investigations were conducted, also under
the sponsorship of the Patent Office, on some aspects of the organization
of scientific and technical information that relate to methods of classifi-
cation, storage, search, and retrieval, for automatic information systems.
Additional studies required for the picture-description matching program
concerned flow problems, the structure of generalized matching of graphs,
Boolean matrices, binary relations, and the formal aspects of disaggregation
as related to forming interest classifications in models of information systems.

The project of mechanizing Patent Office searches for chemical compounds
has reached the point of a completed experimental file of chemical structures
containing 2400 entries. The encoded data cover more than 160,000 or-
ganic compounds. The HAYSTAQ search routine was operated on this
file to test the search logic and determine areas of possible improvement,
using about 385 different questions. Studies of the most frequent errors
and variation in error sources were based on analysis of key-punching output
and computer-based error checking. Research on file organization con-
tinued with the development of screening methods permitting increased
search efficiency.

Ciphering rules originally developed at the Patent Office for representing
chemical structures simply and uniquely were revised and expanded jointly
by the Bureau and the Patent Office. Use of the rules was simplified and
they were made more widely applicable, now covering, for example, optical
isomerism and isotopic labeling. The rules are being expanded to include
inorganic structures, further types of polymers, Markush (variable) struc-

134

tures, and partially indeterminate structures. An experiment is under way
to test the adequacy of ciphers for data input and as the basis of screening
and searching. The logic was worked out for a number of the manipula-
tions necessary on the ciphers, and some preliminary computer runs were
made.

An overall systems design was prepared for the Office of Technical Serv-
ices (Department of Commerce) to aid it in managing the information
associated with acquiring, advertising, and disseminating the report litera-
ture stemming from Government-sponsored research and development. The
plan includes progressive mechanization of index preparation, announcement
composition, processing requests for documents, inventory control, and
processing documents into the OTS collection.

An experimental computer program for producing a permuted title index
of technical reports is now completed. Another program operating on the
same input was written to produce indexes by subject, corporate source,
series number, contract number, and author.

Sales statistics were gathered, and orders and incoming correspondence
were sampled to evaluate demand as a factor in determining prestocking
and reprinting requirements. Information to give indications of user pref-
erence, ordering habits, and responsiveness to prices was also developed and
evaluated. Based on this information, work was continued on the design of
the mechanized order-processing system to incorporate inventory mainte-
nance and control and the ability to produce operational statistics.

The design of a central machine file to simulate the functions of a massive
card catalog was begun. The data-preparation scheme, the file-building
programs, and the file-maintenance programs are sufficiently advanced for
use in the various index programs and parts of the analyses of sales, users,
and inventory.

Technical Assistance for Data Processing, Expanded assistance to
laboratories at the Bureau identified potential areas for automatic data re-
cording and processing, many of which had special data-logging and pre-
processing problems. Technical assistance was provided following analysis
to determine whether analog or digital techniques were applicable, after
which the feasibility of the selected applications was demonstrated. Ex-
amples are the modular data-logging systems designed for use in experi-
ments concerning the radial properties of magnetically contained plasma
arcs formed at low and near-atmospheric pressures.

The program of developing modular units of data-logging equipment
for use by other laboratories included the design, construction, and evalua-
tion of the following modules: a digital multiplexer functioning as a 64-pole,
three-position switch when used in conjunction with the shift register; a
block reader reading punched paper tape in 12-character blocks; a relay
register storing 16 four-bit characters in terms of relay contact positions;
a ripple register storing up to 10 characters in a way permitting conven-
ient data rate buffering; a counter interface matching the control and data
signals of a commercial counter to the modules; a control auxiliary con-

714-691 0—64 10

135

taining counters, flip-flop multivibrators, and one-shot multivibrators used
in system control; an incremental digital magnetic tape recorder; and special
modules providing nonstandard functions unique to an individual system.
The use of a data processor in a real-time data-logging system was in-
vestigated for multiparameter experiments in nuclear physics. Assistance
in the logical design of input instrumentation, consisting of converters,
counters, timers, and buffers, was provided to the NBS Betatron Laboratory,
and drawings and wiring tables were prepared. Programming assistance
was also furnished in developing routines for handling the input data, pre-
processing, output, and the various forms of display. Methods of setting
up and modifying the experiments are being considered, including a flexible
system for reassigning priorities to four simultaneous experiments.

Information-Processing Systems. A remote inquiry station was de-
signed for the Patent Office to provide easy and rapid communication between
human operators, at their respective locations, and a central data proc-
essor. The design is such that the locations could be within one building
or separated by distances of hundreds or thousands of miles. The remote
station design includes a console with a keyboard for encoding messages, a
visual display similar to a television picture, means for error correction and
control, a local memory, a transmission buffer, and a printer. The design
is compatible with the data-logging system requirements anticipated at the
Bureau. Alternative data-storage devices were investigated, and magne-
tostrictive delay lines were selected as meeting all operational requirements.
Assistance was provided in the development, under the sponsorship of
the Navy's Bureau of Supplies and Accounts, of an efficient system for the
procurement and distribution of the thousands of items within the Naval
establishment by controlling their purchase, storage, and distribution. The
present and planned functions and requirements of the systems were
analyzed, and the characteristics of the equipment needed to be in-
corporated in the new system were determined. Programs for an in-
terrupt-type of entry into the Newport Supply Depot from Boston were
assembled, the availability of suitable equipment was studied, and a mini-
mum system was designed and partially tested. A dial-box entry device
was designed and a prototype is being constructed. A system concept for
computer operation to intergrate the entire Naval Supply System is under
development and points of trade-off between methods of operation and
communication loads were noted.

A modest information-handling system was designed for the Naval Intelli-
gence Agency to provide an efficient, low-cost means of storing, searching,
and retrieving intelligence data. The design incorporates a modified micro-
film camera, an eight-channel keyboard, paper-tape reader and punch for
input-output, a viewer modified for printing, a magnetic drum memory, a
camera modified for one-to-one microfilm copying, and custom-built plug-in
electronic modules. Assistance was also provided in the development of a
more efficient coding scheme for indexing the files.

136

Information handling system designed for the Naval Intelligence Agency as a
low-cost means of storing, searching, and retrieving intelligence data. (See
p. 136.)

The design, development, and construction of ACCESS (Automatic Com-
puter Controlled Electronic Scanning System), a high-capacity, multipur-
pose data-conversion and data-editing system, were continued. ACCESS
is being made under the sponsorship of the Office of Emergency Planning
for handling resource evaluation and status information. The system is
primarily to gather and prepare data from marked documents; it is an ad-
vanced development of the FOSDIC (NBS-Bureau of the Census) and AMOS
IV (NBS- Weather Bureau) systems that will, when completed, serve civilian
defense needs.

The data processor is designed to control not only the scannjer but also
communication facilities, pen plotters, and multiple tape units. It performs
such operations as table lookup and memory intertransfer, rendering it
adaptable for code conversion, verification, editing, reorganizing, screening,
control of input-output devices, and preparation of output messages. The
central data processor and the flying spot scanner and control of the system
are now completely constructed while the plotter system, communication
portion, and magnetic tape control unit are designed.

The application of automatic data-processing techniques to processing
hydrographic data, from shipboard data logging to the production of charts,
was studied for the Coast and Geodetic Survey. Specifications for a data-
processing system incorporating a computer and peripheral equipment were
prepared for the Survey as the basis for procurement.

137

The Air Force Systems Command sponsored the beginning of a long-
range project to develop plans and specifications for an information-process-
ing and information-control system of a worldwide range for support of
future orbital and space programs. Basically, the system must provide
means for optimum effective use of instrumentation, communications facil-
ties, and central control, obtaining mechanization of the range "countdown,"
coordination of instruments at all stations, processing data at remote sites,
and controlling the flow of commands and reports in communications links.
Preliminary work was conducted, specific problem areas were delineated.
and work was begun toward the establishment of absolute time on a global
basis

Engineering Applications and Devices. Technical assistance to the
Defense Communications Agency was continued to devise and use a com-
puter program simulating the Defense Communications System. The DCS
controls a worldwide communication system, a composite of the separate
long-line communication systems of the three Services, providing communi-
cations for defense and related organizations regularly and during emergency.
The Bureau provided consulting services on the performance simulation
model of the network being developed by a contractor, and undertook chart-
ing the inputs and programs required in the simulations, permitting analysis
of vulnerability, recuperability, performance, and economics.

Advisory services were provided to the Bureau of Naval Weapons in con-
nection with its contracts for research in the area of direct digital encoding
devices. Two developments were considered: a digital pressure transducer
on which assistance was given on the digital logic circuitry and mechanical
characteristics of the pressure-sensing elements, and a unique coding device
utilizing the varying electric field on a conductive substrate.

A data-logging system for sampling and compiling analog and digital data
into a format suitable for transfer onto magnetic tape was extensively modi-
fied for the Army's Harry Diamond Laboratories. Analog information
can now be transcribed by it onto magnetic tape in IBM format. This
equipment is for use in the collection of experimental data throughout the
laboratories.

A prototype personnel peer-rating machine, for rapid performance meas-
urements and evaluations of leaders, was designed and a prototype delivered
to the Army Personnel Research Office. This machine is now scheduled for
comprehensive evaluation at the Army Training Command, Fort Ord, Calif.,
under actual conditions of use.

The Vigilometer, a versatile laboratory device for presenting audio and
visual questions to a human being and recording his responses, was designed
and a model is now under development. The system is intended to deter-
mine the alertness of the human in a control loop and his fatigue threshold.
Detailed engineering specifications were prepared, and fabrication and
wiring are more than half completed.

Special Studies and Analyses. Research and development on tech-
niques for scanning serial stereophotographic information were continued

138

under the sponsorship of the Naval Training Device Center. The object
of this program is to use the scanned information for automatically pro-
ducing three-dimensional terrain information. The input material, in the
form of a photograph or other pictorial material up to 9 in. X 9 in., is scanned
by an experimental drum scanner linked to an analog-to-digital converter.
The magnetic tape output obtained represents each successive 0.005-in.
square picture element by one of eight gray-scale levels.

Several test programs for the IBM 7090 computer were written to process
the magnetic tape carrying the encoded pictorial data. These programs
analyze the digital data and present the information in various ways — spot-
by-spot detail, a list of runs, a three-line average, a basic eight-level pictorial
printout, experimental four-level and five-level pictorial printouts, and a list-
ing of key trend points.

The Bureau provided consultative services to the Weather Bureau, both in
activating Automatic Weather Stations previously developed by the Bureau
and in transmitting and processing photographic data transmitted by the
new weather satellites of the NIMBUS series. The NBS services included
a review of the Weather Bureau data-processing capabilities and an investi-
gation of techniques for producing large photographic cloud history archives.

The U.S. Air Force requested and received assistance in the evaluation
of two contractor proposals. One was for the design, manufacture, and
installation of a General Purpose Automatic Test System (GPATS) for

Rapid measurements of performance, and evaluations of leaders can be made
with this prototype personnel peer-rating machine developed for the Army.
(Seep. 138.)

139

more effective depot level maintenance of modern airborne electronic systems.
The other was for proposed designs for a Versatile Automatic Test Equip-
ment (VATE), to be used in the repair and testing of the Inertial Guidance
System, making the most of versatility and standardization of test equipment.

The continuing study of the system requirements for automatic data
processing at NASA's Goddard Space Flight Center concentrated on a
survey of commercially available magnetic tape-to-tape digital data-transmis-
sion systems. Technical advice regarding interconnecting the several NASA
computer facilities via high-speed data links was given, including recom-
mendations for microwave transmission equipment and high-speed data
terminals.

Management Data Processing, Technical assistance was continued
to the Public Housing Administration concerning data-processing techniques
and programming for reports on housing applications. The computer pro-
grams were revised to reflect the requirements of new legislation concerning
the administration of Federal-assisted, low-rent housing. Data about appli-
cants for tenancy in low-rent housing, in addition to data about tenants
already in residence, are submitted by the local housing authorities for
annual review to determine tenant eligibility. New computer programs
were written for processing data on approximately 500,000 reexaminations
and 120,000 new tenants annually.

The activities and operations of the Interstate Commerce Commission were
analyzed to determine the areas in which the use of automatic data-processing
techniques was feasible. Systems and computer programs were designed
for applying these techniques to cost-finding studies of motor and rail
transportation, for providing information on authorities granted to motor
carriers, and for obtaining information on caseloads and the time required
for administrative proceedings.

Automatic Mail-Sorting Developments. The Bureau continued its
assistance to the Post Office Department's Office of Research and Engineering
in applying automatic data-handling techniques and equipment to mail-
sorting and route-selection operations. A revised computer program was
developed for selecting optimal paths for routing mail, using scheduled
transportation links. The new program, designed to aid in a semiannual
problem, can handle 84 nodes (airports) and 2000 links (scheduled trans-
portation segments).

A procedure for partitioning transportation networks was developed, in
which the network is considered as a graph which can be divided, by the
elimination of selected nodes, into several subgraphs having no common
points. This demonstrates that a large variety of transportation networks
can be partitioned by the elimination of a surprisingly small percentage of
the nodes. Work in this area should lead to procedures for determining
optimal paths when handling larger networks.

The study of updating files in a codesort system was continued, and
an improved procedure developed for updating the incoming file. Programs
were written enabling the computer to use these files in preparing standard

140

Post Office documents.

The network study of the sorting and transportation problem was continued
and a mathematical model developed to represent the important properties
of a postal transportation network. Further assistance was given to the
Post Office Department in the technical monitoring of a large-scale simulation
project and human factors study.

2.3.3. INSTRUMENTATION

The Bureau is concerned with both the theory and practice of measure-
ments; its practical work is aimed at improving both industrial technology
and the Bureau's own research programs. Since measurement precision
depends on the natural limitations of the method and the behavior of prac-
tical instruments, both are being investigated to advance the measurement
art.

The Bureau maintains an extensive reference file of literature on instru-
ments and measurement methods to help disseminate measurement infor-
mation and avoid duplicating scientific research effort. The file is designed
so that its data can be retrieved partly by mechanical means. Simple tech-
niques insure good coupling between the researcher and the file, so that the
researcher is led quickly to relevant information.

Mechanical t instrument activities include responsibility for the national
standards of humidity and for improvement in standard hygrometers and
humidity generators. Calibration methods are being developed for pressure
and acceleration transducers, while other mechanical instruments are being
developed to meet specific Federal agency needs.

Electrical and electronic methods are widely used in modern instrumenta-
tion, even when the initial phenomenon being measured is not electrical in
nature. Electronic methods were devised to investigate the characteristics
of materials used in vacuum and semiconductor electron devices and the
behavior of very high vacuum systems, as well as the characteristics and
capabilities of electron devices themselves. Improved electronic instruments
were developed not only for use in Bureau research programs but also for
use by other Federal agencies.

Failure Anticipation by Semi- Automatic Techniques, For a num-
ber of years, the Navy Bureau of Ships has supported an NBS program for
developing electronic equipment fault-location techniques. The success of
work in the fault-location project led to new thinking on the old idea of a
failure-anticipation system, an area demanding of development efforts.

Electronic equipment failures can be anticipated by recording and analyz-
ing equipment performance data. The failure-anticipation methods devel-
oped at the Bureau do not employ computer techniques or special interpreting
equipment, and thus are relatively simple and versatile. After the recorded
data are used for anticipating failures, they can be put to further use in
studies of equipment reliability. Such analysis of recorded performance
data should permit identification of incipient troubles before they become
major problems.

141

In project FIST, a system for testing and maintaining modularized electronic
equipment was developed which requires no more than bulk-changing skill on
the part of the maintenance personnel. (See p. 141.)

Hall Effect Measurements. The Hall effect, in which a potential is
induced by current flow across a magnetic field, was discovered in 1879
but only recently became widely used in electronic instrumentation. The
present popularity of Hall devices led the Bureau of Naval Weapons to
sponsor a program at the Bureau to establish standard measuring methods
and terminology for Hall effect devices.

A proposed standard for Hall generator definitions, terminology, letter
symbols, and graphic symbols is in preparation. Included are definitions
of linearity error and descriptions of measuring methods. The Bureau
joined in organizing a meeting of the American National Committee for
the International Electrotechnical Commission (TC 47) to prepare an Amer-
ican proposal for Hall-device standards. The military standard prepared
by the Bureau for the Department of the Navy was used as a basis for the
American proposal.

Instrumentation using electron paramagnetic resonance to measure small
magnetic fields in restricted areas is being developed.

Vacuum Physics. Precise measurement techniques in the very high
and ultrahigh vacuum regions are urgently needed, particularly for studies
of particle density. The program is now concerned with obtaining more
precise measurements of conductance at these low pressures, to make possible
better understanding of particle distributions and accurately known con-
ductances to be used as reference standards for ionization gage calibration.

Substitution techniques are being studied for measurement of vacuum flow,
since substitution methods are in principle independent of detector charac-

142

teristics, gas species, and temperature. Successful use of substitution depends
upon good detector sensitivity, lack of detector hysteresis, and on calibra-
tion and resolution of the variable conductance against which the unknown
is compared. A scheme for calibrating the variable conductance against
zero-thickness orifices was evolved, and glass rotary valves with specially
shaped orifices were produced as variable conductances. Ion gage emission
was regulated to 0.1 percent. An experimental vacuum line with these
components demonstrated that changes in the variable conductance of 0.1
percent and changes in. pressure of less than 0.1 percent at 5X10-6 torr
can be resolved. This resolution indicates that substitution procedures are
feasible.

A Photoelectric Ratio-Measuring System for Incident Light.
Measurements of absolute light intensity at selected points are normally
subject to the effects of fluctuation of the source during the measurement
period. In developing an instrument for measuring the field distribution of
bremsstrahlung radiation from a synchrotron, the electronic instrumentation
laboratory developed an instrument for measuring the intensity at a fixed
point relative to that at another position. The ratio of the two fluctuations
originating at the common source must be independent of source fluctuations
and must be due to variations in either of the two flux paths.

In the ratio-measuring instrument one phototube was fixed in the light
beam and the other mounted behind a slit that could be moved across the
beam. The ratio of the measured quantities gave a relative amplitude plot
of the radiation beam that was independent of random fluctuations at the
source. The light flux arrived at each phototube in the form of pulses.
Variable gating circuits allowed independent selection of the measuring
interval within the radiation pulse cycle. Ratio measurements were made
with a modified strip chart recorder; digital voltmeters also can be used for
ratio indications.

A precision electronic integrator was developed as a companion unit to
the ratio-measuring instrument for absolute measurement of radiation yield
by derivation from a time-integration of photoelectric current. The inte-
grator has a time constant of about 10 days; thus a charge on the integrating
capacitor decays at a rate of about 0.5 percent per hour. Linearity as
checked with a timer and a digital voltmeter is approximately ±0.01 percent.

Proportional Temperature Controllers. The first work on propor-
tional control of temperature by the Electronic Instrumentation Section was
begun in 1947. Since then, 16 different models of temperature-control
instruments have been developed for laboratory use within the Bureau. Each
new model has represented an improvement in accuracy, dependability, or
versatility.

Present systems using resistance thermometers can react to a temperature
change as small as ±0.001 deg C to produce a compensating control of
heater power. It is possible to increase this sensitivity to differences as
small as ±0.0001 deg C. Many systems having high sensitivity react un-
stably, however, producing a periodic oscillation in temperature. Thermal

143

time lags in the controlled environment are one source of such instability,
so the environment must be designed carefully if high system sensitivity is
to be obtained.

Recently designed controllers use thermistors as temperature sensors be-
cause of their high sensitivity and low cost. Their electrical stability is
questionable, however, so they are currently restricted to applications re-
quiring a control accuracy no better than ±0.01 deg C. The newer con-
trollers have the advantage of adjusting heating power continuously, as
opposed to older systems using on-off, or time-proportional, control.

Replacing vacuum tubes with semiconductor devices made temperature
controllers much more reliable. Transistors, for example, operate at lower
circuit voltages and with less internal heating. Future work is directed
toward even simpler and more reliable designs.

Hygrometry. The Bureau completed the development of a pneumatic
bridge hygrometer which is suitable for use as a secondary or laboratory
reference standard. This instrument contains four critical-flow nozzles,
with a pressure manometer across the bridge, and a desiccant in one branch.
The differential pressure across the bridge is a measure of the moisture con-

Pneumatic bridge hygrometer developed for use as a secondary or laboratory
reference standard for humidity measurements. (See p. 144.)

144

tent of the test gas flowing through the bridge. The bridge was calibrated
against the NBS gravimetric hygrometer; in the range of 0.6 to 19 mg water
vapor per gram of dry air, it measures the humidity of the test gas (in
terms of mixing ratio) with an accuracy of ±0.06 percent of full scale.

A preliminary intercomparison between the Bureau's two-pressure hu-
midity generator and the Bureau's gravimetric hygrometer reconfirmed
that the generator produces atmospheres of known mixing ratio with an
accuracy of ±0.5 percent or better.

Electromechanical Transducers, The Bureau is engaged in a con-
tinuing study of the behavior and performance of electromechanical trans-
ducers, particularly pickups sensing such parameters as pressure and ac-
celeration. This program is jointly sponsored by the Bureau of Naval
Weapons, the Air Force, and the National Aeronautics and Space Adminis-
tration.

An experimental technique using shock tube excitation was developed
for obtaining the resonances, particularly the lowest one, for a variety of
flush-mounted, high-frequency pressure transducers. The technique con-
sists essentially of subjecting the transducer to a pressure step function
inside a shock tube. The transducer output is applied simultaneously
to an oscilloscope (for a photographic record) and to a magnetic drum
recorder. This recorder preserves the transducer's indication for repeated
playback into a spectrum analyzer. The analyzer produces a histogram
showing the frequency components present in the transient and, roughly,
their relative amplitudes.

Selected transducers were calibrated, tested, and evaluated to keep
abreast of the newest commercially available pickups and to determine the
adequacy of test methods and equipment.

Instrument Reference Service, Industrial and Government scientists
developing instruments of any kind must know what has already been done
in the same area in order to design without duplication of effort. A scientist
seeking information on work already done in his field can make inquiry
of the Instrument Reference Service, one of the Bureau's reference and con-
sultation services for scientists.

The Instrument Reference Service enlarged its card index of instrumenta-
tion literature by selecting, analyzing,, coding, and recording additional in-
formation on the special punched cards of the "peek-a-boo" system. Inquiries
are answered by means of the index and other information resources.

A number of improvements in the indexing system were made: a simple
photographical method of reproducing sets of punched cards was developed.
This not only facilitates replication, but the positive and negative copies ob-
tained can be assembled as logical-sum and logical-negation searches. Micro-
cite, the information-searching machine developed at the Bureau several
years ago, now is in routine operation performing searches for instrumenta-
tion information. An improved machine having a potential search capacity
of millions of abstracts is now under development and will be tested in use
during the next fiscal year.

145

2.3.4. RADIO PROPAGATION

The Central Radio Propagation Laboratory (CRPL), located at Boulder,
Colo., has the primary responsibility within the U.S. Government for collect-
ing, analyzing, and disseminating information on the propagation of radio
waves at all frequencies along the surface of the earth, through the atmosphere,
and in space. Some work of the Bureau is international, both in the origin
of data and because it is performed in cooperation with scientific groups of
other countries. This is particularly true of CRPL's participation in the
recent International Geophysical Year (TGY) program and in the Interna-
tional Years of the Quiet Sun (IQSY) program to take place in 1964 and
1965.

IQSY. Several members of the CRPL staff are participating in plan-
ning the scientific programs for IQSY. CRPL also prepared the Manual
for World Days Program and the International Geophysical Calendars for
IQSY. These provide the framework for coordinating many aspects of the
scientific programs recommended for each of the IQSY disciplines: meteorol-
ogy, geomagnetism, aurora, airglow, ionosphere, solar activity, cosmic rays,
and aeronomy. The details of these programs call for special observations
on certain days during IQSY or special treatment of the data obtained. The
rapid communications necessary during the World Days program will be
obtained by channeling messages principally through Regional Warning
Centers (RWCs). The North Atlantic Radio Warning Service at Fort Bel-
voir, Va., will serve as the Western Hemisphere RWC, and also as the World
Warning Agency responsible for declaring Alerts, days of special geophysical
interest.

The World Data Center— A for Airglow and Ionosphere was relocated and
plans made for handling the high rate of data inflow which will begin with
the IQSY. Microfilming is being considered to improve cataloging and
provide rapid availability of data. All incoming data will be immediately
copied, and the routine exchange of data made on microfilm. The volume of
requests for IGY data has remained high during the past year, indicating
the continued need of this service by the scientific community.

IONOSPHERE RESEARCH AND PROPAGATION

The Bureau conducts and coordinates research on the propagation of
radio waves as affected by the ionosphere and on the special factors (such
as solar flares) which can give rise to large departures from the normal
behavior. It is also concerned with research on the nature of the media
through which these radio waves are transmitted and the interaction of radio
waves with the media. One of the important functions of the Bureau is
the preparatiaon of predictions of radio wave propagation and warnings
of solar and geophysical disturbances.

Geomagnetic Micro pulsations and Infrasonic Pressure Waves.
An experiment combining measurements of geomagnetic micropulsations and
infrasonic pressure waves was carried out in the auroral zone at Fort Yukon.

146

Alaska, during August 1962. The results supported the supposition that
infrasonic pressure waves having periods of 10 to 110 sec and amplitudes
of one to 10 dynes/cm2 have their source in the auroral region. (For a
report on study of infrasonics of other periods.) They are also associated
with geomagnetic micropulsations in the same period range, with ionospheric
absorption, and with fluctuations of the auroral electrojet. The micro-
pulsation pressure front was found to arrive nightly with a consistent time
and directional relationship to the east-to-west progression of the auroral
activity maximum. Despite the general relationship, it was not possible
to find identical geomagnetic micropulsation and infrasonic excursions.
This was interpreted to be a result of reception of infrasonic pressure
signals from nonlocal sources, causing the indication of infrasonic activity
to precede the local auroral activity in the early evening and to extend later
into the morning hours. Variations in the auroral ionospheric heating,
initiated by the local electron bombardment, and perhaps through auroral
electrojet joule heating fluctuations, seem to be a source of auroral zone
infrasonic pressure variations.

These phenomena were investigated by making around-the-clock measure-
ments at Fort Yukon and College, Alaska. Measurements were made at
both stations of infrasonics activity index, changes in riometer absorption
from the "quiet day" value, variation of magnetic field from quiet day
value, and geomagnetic micropulsation activity of period 5 to 30 sec.

Lunar Tide Effect in the D-Region, The presence of a semidiurnal
lunar tide in the daytime Z)-region of the ionosphere (at a height of about
70 km) was established for the first time. The lunar tide produces a varia-
tion in the height of radio reflection of approximately 0.2 km along VLF
radio paths between Panama (Canal Zone) and Boulder (Colo.). A com-
parable value was obtained for the Hawaii-Boulder path. The maximum
height change resulting from the lunar tide occurs two hours before lunar
transit. This work was sponsored by the Department of Defense Advanced
Research Projects Agency.

Effect of VLF Propagation on Standard Frequency Transmis-
sions. Recently, VLF radio transmissions have been employed in the com-
parison of standard frequency oscillators separated by great distances, such
as between various countries. In applications of this type it is of major
importance to determine the errors introduced by the propagation medium.
This has been done by measuring the accumulated phase difference between
an accurately controlled VLF transmission and a local reference oscillator.
It was assumed that any frequency difference between the transmitted VLF
signal and the local oscillator, after correction for known frequency changes,
increased linearly with frequency. The precision of the frequency com-
parison was then found to be 4X 10~10 for observing periods of 1 hour and
at least 3 X 10-12 for periods of 300 hours.

If these errors are not due to differences between the oscillators being
compared, they must be due to the propagation medium. Thus, the figures

147

given represent upper limits to the errors introduced by the propagation
medium for the particular path being observed.

It is interesting to note that the lunar tide mentioned above can intro-
duce appreciable errors in short-term frequency comparisons. The error
introduced along the Canal Zone to Boulder path, for example, could be as
much as 2 X 10-11 during a 6-hour frequency comparison when the path is
sunlit. This work was sponsored by the Department of Defense Advanced
Research Projects Agency.

Ionizing Processes in the D-Region of the Ionosphere. Observa-
tions of the diurnal phase change on long VLF paths at medium and high
latitudes show that the reflection height of the ionosphere drops almost
immediately when the lower ionosphere becomes sunlit. It remains at the
low level until darkness occurs and then rapidly returns to the nighttime
height. Observation at Tucuman, Argentina, of VLF transmission from the
Canal Zone over a path crossing the magnetic equator, however, shows a
quite difTerent diurnal variation. Near noon the height of reflection shows
a dependence on the zenith angle of the sun, averaged over the path. This
may confirm suggestions that were made concerning the ionizing influence
of cosmic rays in the lower ionosphere. This contribution would be much
reduced near the magnetic equator, according to the suggestion, leaving only
the effects of the sun's ultraviolet and X-radiation.

It is well known that solar flares produce sudden reductions in the height
of reflection of VLF signals during daylight hours. It was recently dis-
covered that nighttime reductions of height also occur in association with
magnetic bays. There is a tendency for such events to occur at latitudes
where precipitation of electrons from the outer Van Allen radiation belt
would be expected.

Ionospheric Predictions by Numerical Mapping. The recently de-
veloped Gallet-Jones method of numerical mapping of ionospheric charac-
teristics by modern electronic computer methods was adopted and applied
to the CRPL ionospheric radio propagation predictions. For almost 20
years the CRPL Series D prediction charts, prepared by manual and graphi-
cal methods, have been standard tools of Government and business com-
munication services in the United States and abroad. The predictions are
used in designing communication systems and for frequency planning and
allocation purposes, to ensure the most efficient use of high frequencies.

The new series of CRPL Ionospheric Predictions, which replaces the
former Series D prediction charts, uses numerical prediction maps in two
forms. Tables of predicted numerical map coefficients are provided for
large users which have computing equipment enabling them to make effective
use of the speed and economy of electronic computer methods in applying
the predictions to communications problems. The predicted coefficients
are also available in punched card form for more efficient computations.
World maps of the ionospheric predictions are provided to the small scale
user for the manual solution of communications problems. Polar prediction
maps also are available for specialized high-latitude applications. Not only

148

150* 165' EAST 180* WEST 165'

LONGITUDE

135* 120*

FIG. I B. PREDICTED MEDIAN MUF(4000)F2 (Mc/s)

The monthly NBS radio propagation predictions are now being prepared by
recently-developed numerical mapping techniques with an electronic computer,
and the data is presented in special form for easy input to computer. Graphical
prediction maps (above, for October 1963) are still provided for users who
have no access to a computer. (See p. 148.)

are the new predictions believed to be more accurate than the older type, but
they are also much more versatile for adaptation to individual problems.

First Topside Sounder Satellite, As a part of an international co-
operative program to probe the topside of the ionosphere, the National Aero-
nautics and Space Administration launched the Alouette topside sounder
satellite into a nearly perfect orbit on September 29, 1962. The orbit is
inclined 80.5° to the equator and it is almost circular between 995 and 1030
km altitude. The topside sounder was designed and constructed by the
Defense Research Telecommunications Establishment (DRTE) of Canada
and is controlled by it. It consists of a swept-frequency sounder covering the
range of 0.5 to 11.5 Mc/s in 18 sec. The sounder operated perfectly
following the launch and since then it has produced more than 400,000
ionograms. Such ionograms show the heights at which downward trans-
mitted signals are reflected by the ionosphere as the signal frequency is swept
across its range. The Alouette data are being analyzed jointly in Canada
by DRTE, in the United States by CRPL and NASA, and in England by the
Radio Research Station at Slough.

The high inclination of the Alouette orbit permits study of the topside
of the ionosphere over a very wide range of latitudes from the northern polar
region to the southern polar region. Analysis reveals, among other things,
a transition from atomic oxygen ions to lighter ions at about 600 km at

149

temperate and low latitudes, as well as a tendency for the polar regions to
be substantially warmer than the tropics. The topside sounder has observed
irregularities in the ionosphere varying in size from a fraction of a kilometer
to hundreds of kilometers.

The Central Radio Propagation Laboratory is also involved in a second
topside sounder satellite, which has been constructed under NASA contract
by Airborne Instruments Laboratory. This instrument, a fixed-frequency
sounder operating at six frequencies between 1.5 Mc/s and 7.2 Mc/s, will
be operated by CRPL under NASA support. It will be launched by NASA
on an improved Scout rocket, into an orbit similar to that of Alouette, early
in 1964. Originally set for late 1962, the launch has been delayed several
times, both to avoid solar cell damage resulting from the artificial radiation
belt created in 1962 and to permit further improvement of the experiment
in the light of results from the first topside sounder satellite.

Planetary Ionosphere. Recent theoretical estimates of the composi-
tion of the Martian atmosphere, based on 2 percent C02 and 98 percent N2,
indicate that the Martian ionosphere occurs at a greater height than does
the earth's ionosphere, but at about the same pressure. The maximum elec-
tron density for an overhead sun is probably between the density of the
terrestrial E- and F2-layers, that is, between 105 and 106 electrons per cm3.
There may be, in addition, a layer that absorbs radio waves much more
strongly than the normal terrestrial Z)-region.

Assistance to Project Mercury. During the orbital flights of Astro-
nauts Shirra and Cooper, special efforts were made by the staff at the North
Atlantic Radio Warning Service located at Ft. Belvoir, Va., to keep Project
Mercury headquarters informed of current and anticipated radio propaga-
tion conditions. Special forecasts of radio propagation conditions were
issued every hour during the flights, specifically for the high-frequency cir-
cuits which comprise the Project Mercury ground communications network.
The forecasts were made available to the NASA Communications Director
and the Propagation Analyst at the Goddard Space Flight Center communi-
cations center. During the periods between orbital flights, forecasts were
issued by the Warning Service staff weekly, with daily updating as necessary.
Reliable forecasts were made possible by associating reports of observed
propagation conditions on each Project Mercury circuit with reports of
observed solar, geomagnetic, and ionospheric activity occurring at the same
time. This work is performed under a Memorandum of Agreement between
the National Aeronautics and Space Administration and the Bureau.

The propagation forecasts supplied by the North Atlantic Radio Warn-
ing Service enabled the Mercury ground communications center to antici-
pate problems that might be encountered and select alternative frequencies
or circuits to insure unbroken communications. This reliability of communi-
cation was required in obtaining information from the astronaut and space-
craft equipment, which was telemetered to the tracking stations and relayed
to the Mercury Control Center at Cape Canaveral. The same reliability was
required for transmission of decisions from the Mercury Control Center

150

MERCURY COMMUNICATIONS NETWORK

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Special forecasts of radio propagation conditions were issued by the Bureau
every 30 minutes during the orbital flights of Astronauts Schirra and Cooper.
Such information was essential to effective communications between Mercury
control at Cape Canaveral and other Mercury stations around the world. (See
p. 150.)

to the tracking stations and the capsule itself, to insure the safety of the
astronaut and the success of the mission. The staff of the North Atlantic
Radio Warning Service received congratulatory telegrams from the Na-
tional Aeronautics and Space Administration for its role in making the
missions successful.

Ionospheric Ray Tracing, Ionospheric ray tracing, which takes the
earth's magnetic field into account and allows for a "two-dimensional
ionosphere" (one with the horizontal gradients along the great circle path
of propagation) , is now possible with a new 7090 computer program. This
program is basic to an improved understanding of ionospheric propa-
gation, since its output includes step-by-step evaluation of the ray path. It
can also be applied to theoretical studies of the phase, amplitude, and
frequency of ionospherically propagated radio waves.

This research has been supported partly by the United States Information
Agency and partly by the Air Force Cambridge Research Laboratories.

Operation Fish Bowl. During the past year a number of measure-
ments were carried out for the Defense Atomic Support Agency and other
agencies in connection with the 1962 series of high-altitude nuclear tests,
Operation Fish Bowl. Many complicated technical, logistic, and personnel
problems were met and successfully solved on short notice.

714-691 0—64-

-11

151

Among the variety of support activities, six ionosphere stations were
set up and operated and VLF phase measurements were made over a number
of paths. Observed perturbations of VLF phase following the blast of
July 9, 1962, are attributed to a lowered reflection height in the D region of
the ionosphere, which produces an advance in the phase of the received
signal. Such effects were produced in signals passing through regions illu-
minated by prompt X-rays from the detonation. Effects observed several
thousand kilometers from the detonation probably were associated with the
neutron-beta decay process.

Also, the North Pacific Radio Warning Service at Anchorage, Alaska
was able to observe unusual effects on high-frequency field strength and
on the strength of cosmic noise recorded by a riometer following the
shot. The detonation times were announced by telegram to geophysicists
throughout the world through the facilities of the World Warning Agency
of the International Ursigram and World Days Service. Thus experimenters
the world around were able to study their records for effects of the explosion.

On the occasion of the July 9 event, high-frequency signals being re-
ceived at Anchorage were lost at the instant of the detonation. Recovery
began within a few minutes, but 20 minutes later there was again evidence
on the records of a further increase in absorption. This second onset was
clear on both the riometer recording and the field-strength records. The
source of this later absorption is of considerable interest. Analysis of such
events should lead to better understanding of processes taking place in the
Z)-region of the ionosphere. This work was sponsored by the Department
of Defense Advanced Research Projects Agency.

Thermal Properties of the F-Region. Measurements of ionospheric
electron distributions at 11 widespread locations during the International
Geophysical Year and 1959-1960 have provided valuable data on the solar,
seasonal, and diurnal variations of the F-region. The temperatures inferred
from the curvature of the F2-layer peak are uniform at all latitudes in the
presunrise period and show a steady diminution with decreasing solar ac-
tivity. Daytime measurements suggest that the electron temperature exceeds
the ion temperature at the height of the F2 peak, the ratio Tc/T ',- increasing
with latitude and in the summer. The work also showed that the high electron
densities of the so-called "winter anomaly" of the F-region represent, in fact.
the normal situation, the summer being the anomalous season because of its
abnormally low electron content.

Chemical Release in the Ionosphere. The Bureau participates in a
series of experiments sponsored by the Air Force Cambridge Research Labo-
ratories involving the release in the E- and F-regions of the ionosphere of
substances having high chemical reactivity and observing reactions follow-
ing. In a recent series of such experiments, NBS ionosondes detected the
presence of "sporadic-F" ionization at the exact level of a strong shear in
the neutral wind profile, revealed by viewing a luminous rocket trail, thus
confirming a recently developed theory accounting for the formation of

152

sporadic-^. In another experiment, a rocket released 20 kg of sulfur hexa-
fluoride in the daytime F-region, producing a large region of reduced elec-
tron density through the attachment of electrons to the sulfur hexafluoride
molecules. Ionosondes detected this electron "hole" in the ionosphere and
showed its growth and ultimate decay over a 30-min period.

Electron Density Measurements in the Ionosphere, New develop-
ments, jointly sponsored by the Bureau and the National Aeronautics and
Space Administration, in radio soundings of the ionosphere and in precision
calculation of electron distributions from these soundings are providing
greatly improved detail concerning the structure of the lower F-region. By
extending downwards the radiofrequency range of the sounding equipments
at many of its associated ionosphere observatories, the Bureau hopes soon
to be in a position to prepare a worldwide survey of the occurrence of night-
time ^-region ionization. The measurements also should permit improved
identification of the main levels of absorption of solar energy in the atmos-
phere and will assist study of the influence of the ionosphere on long-distance
radio services.

TROPOSPHERE AND SPACE TELECOMMUNICATIONS

Most efficient use of the radiofrequency spectrum is the aim of the
Bureau's program in tropospheric propagation and radio noise. Attaining
this objective requires a basic understanding of radio wave propagation,
noise, and interference. To this end, theoretical and semiempirical pre-
diction methods are developed and compared with statistical samples of
data on radio wave propagation and radio noise. As has been the custom,
a major part of the effort was carried out in support of the Consultative
Committee on International Radio. Several members of the Central Radio
Propagation Laboratory staff attended the Xth Plenary Assembly of the
CCIR from January 15 to February 15, 1963 in Geneva, Switzerland, in
preparation for the International Telecommunications Union Extraordinary
Administrative Conference on Space Radiocommunication, including Radio
Astronomy, held in Geneva in September 1963-

Reports to the CCIR. A comprehensive report on methods for pre-
dicting radio transmission loss at frequencies above 40 Mc/s was presented
to the CCIR, and a summary of this report was adopted. These methods
were subsequently used to prepare a set of propagation curves for the Inter-
national Frequency Registration Board to use in its planning for African
television broadcasting. A short summary of engineering curves for pre-
dicting the absorption of microwaves by oxygen, water vapor, and rain, and
for predicting sky noise temperatures was also adopted.

An international working party was set up, under the chairmanship of
a CRPL staff member, to examine the theory of figures of merit for a re-
ceiving system limited by receiver noise, external noise, or by other un-
wanted signals and its application to optimum use of the radiofrequency
spectrum.

153

Prediction Methods, A comprehensive report on methods of trans-
mission loss prediction, including a description of the newest methods of
calculating service probability, is being prepared. It includes a discussion
of theory and comparisons with results obtained by a triple numerical
integration. The integral made possible a more adequate investigation of
the problem caused by undesired scattering of conventional terrestrial
radio signals along the beam of a satellite communication or radio astronomy
antenna. Use of the integral also permitted existing predictions of path
antenna gain to be updated and generalized.

Electromagnetic Theory. Computer programs were develoned for
solving diffraction problems by means of the general Fresnel-KirchhofT theory
for diffraction over a single, prefectly absorbing knife-edge, with ground
reflected components on either or both sides of the knife-edgre. Another
computer program, develoned for a special case of the general formulation,
permits calculation of diffraction over two knife-edges; excellent agree-
ment was obtained with laboratory data at 20 Gc/s.

Prediction of limitations on radio tracking of rocket launch trajectories
imposed by the atmosphere was made in further study of the theory of
variance spectra associated with radio phase variations on line-of-sight
paths.

A study being carried out for the Signal Corps, in connection with the
communication problems of an Army in the field, compares the path-to-
path variability of transmission loss observed over irregular terrain with
a statistical model of terrain profiles. This model depends on the variance
spectra of deviations of such a profile from its average slope.

PoinMo-Point Moon Communication. An atlas of ground proxim-
ity losses and impedances for various antennas was prepared as a guide for
planning communications between exploring parties and base installations
on the surface of the moon. This makes it possible to determine receiver
characteristics required to overcome noise and transmission loss at various
distances. Propagation over a sphere having layered ground constants
was extensively investigated in this connection.

Radio Meteorology. The direction of research in tropospheric radio
propagation focused more attention on the physics of the medium. The
effects of the atmosphere on communication frequencies from VHF to the
optical range — with emphasis on refraction, scintillation, and scattering —
necessitated new basic programs in radio meteorology. The turbulent charac-
teristics of the radio refractive index at microwave frequencies were shown to
be chiefly those due to the water vapor of the atmosphere, thus uniting the
efforts of the radio scientists and the meteorologist. It was found that in-
formation on water vapor turbulence can be roughly correlated with refrac-
tive index turbulence. The ease and accuracy of measuring refractive index
variations by radio means can be useful in studying water-vapor variations.
Techniques of studying the vertical structure of the atmosphere from
ground-based radio detectors are being fully investigated. Experiments
include probing the vertical structure of the refractive index by high-powered

154

radar and passive detection of water vapor from the thermal noise emitted
by the water vapor molecule. Passive detection of oxygen, also, would pro-
vide a convenient probe of the vertical temperature distribution.

Efficient Television Assignments. The amount of the radio spectrum
allocated to television broadcasting is quite large, amounting to about one
half of the spectrum below 1000 Mc/s. A recent CRPL study of methods
for making television assignments indicates the feasibility of reducing the
spacing between cochannel and adjacent-channel stations. Interference
effects would be minimized by using precise-carrier offset, alternate trans-
mission polarizations, and receiving antenna directivity.

A sample VHF assignment plan for the United States using reduced spacing
indicates the possibility of a twofold increase in the per-channel coverage.
The most significant increases would be in the number of areas served by
several channels — two or more, three or more, and so on.

Conferences were held between the Bureau and the Federal Communica-
tions Commission to explore various problems associated with implementation
of the plan, as well as possible courses of action which might be undertaken.

VHF Air-Ground Propagation Tests. Continuous measurements of
propagation characteristics for long air-ground paths both within and be-
yond the line-of-sight were continued during the second transmission year
of the Midwest Program on Airborne Television Instruction (MPATI).
These measurements provide a unique set of data in that the transmissions
emanate from an airplane at an elevation of 23,000 ft in the 800 to 900 Mc/s
range.

Although the current MPATI service is for educational television broad-
casting, it made possible a great deal of worthwhile information on trans-

High-flying UHF television station broadcasting educational programs over
Indiana. Signals are studied by the Bureau to examine variations in trans-
mission loss both within and beyond the radio horizon. (See p. 155.)

155

mission loss variation which has application to many other services employ-
ing high terminals, including space-earth propagation.

Refractive Effects in Microwave Distance and Position Measure-
ment Systems. Precision distance and angular position measurements
made with systems involving microwave propagation (such as those used
in geodetic survey work and in tracking missiles and space vehicles) are
subject to errors caused by random fluctuations in the refractive index of the
turbulent troposphere. A series of experiments designed to study these
distance and angular position errors in long-baseline tracking systems,
such as the Air Force Mistram system, was completed. The results include
an analysis of the correlation of atmospheric errors on adjacent radio paths,
as well as the correlation of distance errors on a single radio path with
atmospheric refractive index data.

An experimental study was made of the atmosphere-induced variations
in the amplitude and phase of arrival of microwave signals sent over the
same low-level line-of-sight path, but at slightly different frequencies. The
data analysis included the correlation of phase variations at two frequencies
as a function of fluctuation (power spectral) frequency. This work was
prompted by the high amplitude and phase stability required in the operation
of ground-to-ground calibration and synchronization links in some long-
baseline tracking systems. A program was initiated to systematically study
the dependence of angular position errors on antenna aperture size and on
baseline length and orientation. Experiments are also being conducted
for the Army Engineers to study the feasibility of using microwaves in a
portable azimuth-measuring system.

Surface-Satellite Communication Interference. In the event that
space telecommunications services share frequencies with surface systems,
such as point-to-point microwave systems, isolation between terminals of the
systems will rely on geographic separation and antenna discrimination. It
is possible to make fairly accurate predictions of the service fields of signals
propagated through the troposphere, but little is known about the kinds of
efficient propagation that occur infrequently and cause serious interference.
One source of such interference in the 1 to 10 Gc/s range is expected to be
elevated concentration of rain and hail associated with thunderstorms.

An experimental program was undertaken to determine the effects upon
space communication system performance of forward scatter interference
from thunderstorm cells. Measurements were made at 4.8 and 9.1 Gc/s
over a 180-km-wide area of cells and squall lines containing varying amounts
of rain, hail, and thunderstorm activity. Signal paths having transmission
loss values comparable to those of great circle scatter communications were
observed for cells which were off a great circle route. Forward scatter signals
were correlated with weather radar data to develop a prediction basis. These
measurements will be continued to obtain a reliable basis for appraisals of
interference.

Bandwidth of the Tropospheric Propagation Medium. The
amount of information that can be sent over a tropospheric radio path is

156

Table Mesa site near Boulder, Colo., showing antennas used in studies of the
bandwidth limitation of the tropospheric medium. The data developed will
aid in evaluating comunication systems. (See p. 156.)

limited by the fading characteristics of the medium itself. The degree to
which this limitation is imposed is dependent on may parameters, including
distance and type of modulation.

An experimental program was initiated to investigate the relationship
between the bandwidth of tropospheric scatter paths and the performance of
multichannel, angle-modulated radio transmissions over them. Bandwidth
is determined by measuring the coherence of discretely frequency-separated
carriers and the performance of multichannel systems in terms of distortion
present in the received signal. Previous work indicated that the customary
criterion for coherent bandwidth results in a path-bandwidth determination
somewhat less than the bandwidth used in successfully operating tropospheric
scatter systems. The present program is designed to explore new criteria
for coherent bandwidth which will correctly indicate system performance.
Frequency dependence is also being considered in the frequency range from
400Mc/sto5Gc/s.

A suitable prediction formula for the performance of tropospheric scatter
radio systems is a longstanding need; it is estimated that progess in this
area lags transmission loss prediction methods and equipment developments
by several years. The path-bandwidth studies in progress will result in the
determination of a suitable method for predicting the performance of tro-
pospheric scatter radio systems in terms of voice channel signal-to-noise ratios
or telegraph error rates. The limitations due to distortion of multipath
propagation through the troposphere will be taken into account. Thus, the
present program will result in a substantial contribution to the state of the
art of tropospheric scatter systems.

157

Radio Noise Predictions, Atmospheric radio noise, originating from
worldwide thunderstorm activity and propagated via the ionosphere, repre-
sents the irreducible interference level with which a signal must compete
at a receiver in the high-frequency portion of the spectrum. Accurate
prediction of this noise on a worldwide basis is vitally important to users
of this portion of the spectrum.

Improved predictions are now being provided by means of corrections
to previously prepared CCIR Worldwide Prediction Charts. These correc-
tions were prepared by evaluating data collected in the CRPL worldwide
noise-recording network, using several unique electronic computer programs.
Besides improving the prediction of noise power, these corrections make
possible for the first time predictions of such additional parameters as
deviation of the envelope voltage from that producing the average power.
Estimates of the reliability of predictions are presented in the form of
standard deviations for each parameter.

NBS studies of variability of radio noise over large water areas are carried out
aboard the National Science Foundation's Floating Antarctic Research Station,
the USNS Eltanin. (See p. 158.)

Floating Noise Recordings, For the first time, quantitative, objective
radio noise measurements were made from a floating radio noise station.
These measurements began with the installation of an ARN-2 radio noise
recorder aboard the National Science Foundation's Floating Antarctic Re-
search Station, the USNS Eltanin. Radio noise data were gathered at eight
frequencies between 13 kc/s and 20 Mc/s during the cruises, lasting up to
80 days, made in the last year. The recordings were made primarily from
about 40° south latitude to the edge of the Antarctic ice pack, and from
about 50° west longitude to about 85° west longitude. From the preliminary
analysis of these data, it appears that very interesting information on the
variability of the radio noise over large water areas will be obtained.

158

Automatic Data Analysis Facility. The service provided by its au-
tomatic data analysis facility is an important phase of CRPL activities.
The data analysis instrumentation center was established to process auto-
matically data recorded on a magnetic tape medium. Playback-to-recorded
speed ratios as high as 100 : 1 can be selected to attain extremely rapid data
handling.

The data analysis facility provides, in addition to general data trans-
lation to put data into a format for use on large scale digital computers, sev-
eral types of complete analyses by means of special purpose analog and
digital systems. These systems operate on the data read directly from
the magnetic tape in either direct or the frequency modulation mode.
Typical analyses include those of power spectral density, multichannel
distribution for amplitude and fading characteristics, continuous auto- and
cross-correlation as a function of fixed time lag and averaging time, dynamic
autocorrelation yielding an automatic plot of the correlogram as a function
of time lag, and other general analog and digital techniques for measuring
signal parameters.

Included in this facility also are special instrumentation systems for auto-
matic time-code searching and control of tape, nonlinear function generation,
and other automatic data control and conditioning functions.

Instrumentation research associated with the facility has proved to be of
great benefit to many outside agencies, as well as to the Bureau.

RADIO SYSTEMS

The Bureau's radio systems program provides technical information
on radio propagation factors affecting design and use of radio systems. The
emphasis of this work is on long-range radio transmission problems and
methods of measurement for radio communication, navigation, timing, de-
tection, and positioning systems. Radio wave propagation studies are
carried out for ionospheric, groundwave, and line-of-sight paths to define
the limitations, disturbances, and capacity of the transmission medium as a
channel. The information obtained is directed toward guidance of engi-
neering practices, allocation and use of radiofrequencies, and evaluation
of system capabilities and limitations. Standards and methods of measure-
ment are developed for radio systems to fulfill the needs of federal agencies
and industry involved in radio communication operation and regulation.
Studies of modulation, antenna design, information theory, and coding
are directed toward improvement of the reliability of systems and to the
efficient utilization of the radiofrequency spectrum. Consulting and advisory
work is done in accordance with the needs of other government, commercial,
and scientific agencies.

High-Frequency Ionospheric Radar Research. Radar observations
of long distance, high-frequency, backscattered signals are being made to
provide needed information about the size, velocity, and direction of motion
of ionospheric irregularities and their relationship to HF radar and com-
munication problems. One observing technique, using a new 12 to 25

159

Mc/s high-resolution azimuthal scanning antenna, permits surveillance of a
large area of the ionosphere (of the order of 106 sq km projected) with
a resolution of about 50 km. Analog signals of the backscatter energy
at fixed frequencies are recorded on magnetic tape and then digitized for
input to the 7090 computer for analysis. The computer program averages
the backscatter amplitude returned from identified cellular units of range
and azimuth and subsequently plots it. Variations of the amplitude contours
with time provide information about the motions of ionospheric irregulari-
ties. An elevation-scanning array operable over the same frequency range
has been constructed for use in conjunction with the azimuthal scanning
array.

A second technique used in making backscatter observations is that of
sweep frequency measurements with either fixed antennas or a rotating log
periodic antenna for transmitting and receiving. Ionospheric irregularities
are evidenced on the backscatter record as intensification in the signal
amplitude over a range of frequencies which changes with time, the ampli-
tude being related to the speed of motion of a focusing irregularity in the
ionosphere. An investigation was made, on a limited data sample, into
the frequency dependence of the apparent speeds of the irregularities as a
function of the observing frequency. This dependence was found to be
37.5 km/hr/Mc/s, with lower speeds being found for the higher observing
frequencies. Mean speeds of the irregularities ranged from 900 km/hr at
12.5 Mc/s to 570 km/hr at 22.5 Mc/s.

Preliminary analysis of the spectrum and amplitude distribution of fad-
ing HF backscatter signals was begun. The fading spectrum at a given

Erection of an antenna at the NBS Erie (Colo.) field site for radar studies of
ionospheric irregularities. (Seep. 159.)

160

range contains components of several cycles per second down to a few cycles
per hour. The low-frequency components are related directly to the passage
of irregularities through the range of observation. Thus the low-frequency
components at one range would correlate with those at another range at a
different time. An estimate of the velocity of irregularities should be obtain-
able from this information.

Continuous- wave transmissions of high phase stability at 2.10 Mc/s and
4.055 Mc/s were made on a near-vertical incidence path. Phase-path and
group-path data on these transmissions were obtained to ascertain the natural
variations imposed upon such signals due to variation of ionization in the
ionosphere and motions of irregularities through it. Changes in the phase
path of the radio wave are measured by comparing the phase of the wave
reflected from the ionosphere with that of the ground wave direct from the
transmitter. Recording equipment capable of indicating rapid phase change
occurring in time intervals less than a millisecond has shown that Doppler
shifts up to 600 c/s occur frequently and last for a few milliseconds. Such
Doppler shifts were found to occur more frequently at night and are par-
ticularly frequent during spread-/1 conditions. Some of these Doppler shifts
are very likely the result of signal reflection from meteor trails.

Solar Flares. Phase-path observations made at times of solar flares
have shown that solar flares of optical importance 1~ usually provide sufficient
additional ionization below the reflecting point in the F-region to be detected
by phase changes in the 4.055 Mc/s transmission. Only occasionally does
the 2.10 Mc/s transmission, which is reflected from the ^-region, show identi-
fiable phase changes due to the small flares. The rate of phase-path change
for 58 solar flares, measured at 4.055 Mc/s at the time of onset of the
radio effects, has shown a median value of about 10 wavelengths per minute.
For only 10 percent of the flares observed did the onset phase path change
exceed 24 wavelengths per minute. The median duration of phase change
resulting from these flares was five minutes. Neither the phase-path rate-
of-change nor the duration of the radio disturbance seems to be directly
associated with the flare importance.

Modulation Research. Theoretical and experimental studies of mod-
ulation, detection, and coding techniques, the characteristics of time-varying
propagation media, and their relationships were continued. Experimental
studies were made to test the thesis that the limitations imposed on FM trans-
mission by the correlation bandwidth of the medium pertain to the maximum
modulating frequency, rather than to the deviation or maximum excursions
of radiofrequency. FM communication tests over a 1295-km long, 50 Mc/s
ionospheric-scatter circuit were conducted to determine the quality and
distortion suffered by signals using various modulation indexes correspond-
ing to deviations from less than to greater than the correlation bandwidth
of the medium. Using a number of listeners, hearing tests were made of the
recorded voice signals to determine subjectively the quality of the signals for
the various modulation indexes. It was found that the quality improved
with increasing modulation index and with the frequency deviation well

161

beyond the 5-to-7 kc/s bandwidth of the medium, as earlier determined by
fading correlation measurements.

Theoretical studies of error-detecting and -correcting codes continued
with an analysis of a combinatorial problem pertinent to the theory of
runs. The solution obtained applies to the decoding of cyclic codes and
leads to a particular simply instrumented error-detecting and -correcting
decoder. The Department of Electrical Engineering at the University of
Colorado completed a study of short error-detecting codes for the Bureau.
Theoretical studies were made at the Bureau of the probability of binary
errors as a function of average signal-to-noise ratio for a number of modula-
tion techniques subjected to Gaussian noise and a gamma fading model.
This model is more comprehensive than the commonly-used Rayleigh model
and allows for a variety of short-term fading statistics. Studies were also
made of the probability of binary errors as a function of average signal-
to-noise ratio for a signal subjected to atmospheric noise and Rayleigh
fading. Although atmospheric noise has a considerably different amplitude
distribution than Gaussian noise, the study showed the element error proba-
bility to be little different than for Gaussian noise when Rayleigh signal
fading occurs. Work is being continued to consider other fading models
and a variety of modulation-detection techniques.

Digital Errors. Five flexible digital logic equipments were installed:
they can be programmed by patch panels to provide a variety of instru-
mentation quickly and easily for future digital communication experiments.
An experimental program was started, using this equipment, to obtain the
distribution of digital errors in a high-frequency communication link using
frequency-shift keying. Simultaneous oblique soundings of the ionosphere
over the same path will be used to relate the error distributions to the propa-
gation conditions. The purpose of the planned experiments is to obtain the
information necessary to design more efficient digital error-detecting and
-correcting codes for such links.

Testing Facsimile Equipment. The performance of four types of
facsimile equipments was measured for the Air Force. A test chart was
designed to present recording density, resolution, and legibility. Mechani-
cal and electrical performance of the equipments was measured in back-to-
back operation and in long-line operation.

Recording Atmospheric Noise. Evaluation and intercomparison of
the performance of radio systems in the presence of atmospheric noise
is difficult because the characteristics of the noise are variable in time,
making desired or repeatable noise conditions nearly impossible to obtain.
A method of overcoming this difficulty is to have a library of atmospheric
noise recordings, exhibiting a variety of characteristics that can be used in
performance tests. However, conventional tape recording of atmospheric
noise is impractical because of the extremely large dynamic range of the
noise. For this reason a wide-dynamic-range tape-recording technique for
atmospheric noise was developed; it extends the range of a conventional
recorder by dividing the noise signal into different amplitude ranges for

162

recording on separate tape tracks. A dynamic range of 90 db was obtained,
using two tracks, over each half-octave bandwidth between 1 kc/s and 25
kc/s and, with frequency conversion, over any 10 kc/s band between 25
kc/s and 500 kc/s. A system obtaining greater dynamic range and band-
width could probably be developed for more tracks with the use of proper
shielding precautions.

Multipath Microwave Transmission. The development of an ex-
perimental microwave system was completed for propagation studies in the
coming year to determine the bandwidth limitations on multipath propaga-
tion of 10-Gc/s signals at several elevation angles. The tests will be con-
ducted by transmitting pulses of one nanosecond duration from a mountain-
top to several lower-elevation receiving sites for resolution of path length
differentials of one foot or more by use of the short pulses. The objective of
the study is to determine if sufficient tropospheric multipath propagation
can occur over nonhorizontal paths to limit the information rate that can
be transmitted between satellites and earth. Ionospheric effects are expected
to be negligible at frequencies above 10 Gc/s.

Antenna Measurements and Research. The principles of electronic
antenna scanning developed at the Bureau in 1959-60 were extended to
scanning in the elevation plane and applied in the HF ionospheric radar
program. A tower 152 meters high was erected on Table Mesa. Ten log-
periodic dipole antennas were arrayed along its vertical length at 16-meter
intervals, starting at 8 meters above ground. By an application of antenna
aperture synthesis it was found possible to improve the aperture efficiency
over that attained using uniform amplitude. The improved "illumination"
is accompanied by current amplitudes varying sinusoidally with height.
The period of the sinusoidal variation determines the angle of departure.
Such current distribution results in an enhancement of gain by approximately
3 decibels and a reduction of the main beamwidth by a factor of 2. The
above comparison is with the same antenna having uniform amplitude il-
lumination and phase advanced (or retarded) uniformly by an amount
proportional to height.

The antenna was erected next to the horizontal array of 25 log-periodic
antennas electronically scanned in azimuth, and is intended to supplement it.
Both operate in the band of 12 to 25 Mc/s and have been designed for HF
ionospheric propagation studies.

Computer Program for Radiation Patterns. A computer program
was prepared to determine radiation patterns of curtain arrays for the
Voice of America. The program was made as general as possible, allowing
for such variations as in the number of bays and elements stacked one above
the other. It presents both the horizontally and vertically polarized fields
as well as the composite power pattern.

Progress was made in applying antenna aperture synthesis to the analysis
of complex electromagnetic fields. A computer program was designed to
evaluate the components of plane wave fields from measured field amplitude
and phase distributions. Strength, polarization, phase, and direction are

163

Azimuthal and elevation electronically-scanned arrays at the NBS Table Mesa
(Colo.) field site are used in high-frequency ionospheric propagation studies.
(See p. 163.)

obtained for each of the several component sources of the field. The pro-
gram was tested, using simulated field measurements obtained from as-
sumed components; the component values were accurately reproduced in
the test computation. Experimentally obtained data likewise were reduced
to original components closely approximating known values.

Frequency Utilization, Services for the computation of HF radio
path performance, with emphasis on the selection of optimum frequencies,
were expanded through the development of faster and more comprehensive
computer programs. Research into improved methods of predicting HF radio
system performance, using ionospheric data, radio noise data, service require-
ments, and antenna and modulation information, paralleled the development
of computer programs.

164

Services using computers to predict HF radio system performance are
divided between the routine prediction and special studies. Examples of
routine predictions are those for operation of the ground communication
complex of the NASA communication system and for monthly predictions
for the wire news services. Numerous special studies were devoted to prob-
lems such as the long-range planning of NASA and VOA facilities and
the Bureau's consideration of relocating standard frequency station WWV.
In connection with development of U.S. policy concerning frequency usage
within the United States, reports were prepared to summarize the technical
considerations in the selection of optimum frequencies for space communi-
cation systems and for HF communication systems.

Radio Navigation Research — Low-Frequency Loran, Through a
unique program involving several agencies, extensive low-frequency iono-
spheric radio propagation data have been obtained at very nominal cost.
This was done in a cooperative program cosponsored by the Bureau, the
Coast Guard, and the Advanced Research Projects Agency of the Depart-
ment of Defense. Since the Loran-C radio navigation system uses ground-
wave transmissions at LF (100 kc/s), several Loran-C stations were asked
to participate in obtaining propagation data. Existing standby equipment
was slightly modified to make reciprocal measurements of the singly-reflected
ionospheric signal over two paths. The paths, a high-latitude path in the
Aleutian Islands and a low-latitude one in the mid-Pacific, were chosen be-
cause of special interest in these regions during high-altitude nuclear tests.

Preliminary analysis of the year's data obtained from the Loran-C opera-
tion over4 the high-latitude path indicates many interesting and unusual
phenomena. Phase and amplitude readings taken every 15 minutes at each
end of a reciprocal path have been analyzed and the known phase and ampli-
tude of the ground-wave vector removed at each data point to obtain the
uncontaminated, singly-reflected, ionospherically-propagated primary signal.

For departure from mean values there was very poor correlation between
phase and amplitude changes at all times; the correlation was calculated to
be less than 0.2 for the entire year. The correlation between phase changes
observed at the two ends of the reciprocal path was approximately 0.6 for a
year's data.

In a separate study involving fast phase changes occurring at the two
ends of the path, only one out of three changes was seen simultaneously at
both ends of the path. The correlation coefficients for the amplitude fluctua-
tions on the reciprocal path range from 0.6 to 0.7 during the day to less than
0.1 during the night.

The standard deviations of both the phase and the amplitude data were
higher during the winter than during the summer, and higher during the
night than during the day for both winter and summer. In general, the
amplitude fluctuations demonstrate poorer reciprocity than do the phase
fluctuations, and both demonstrate poorer reciprocity at night than during
the day. Another interesting observation is that both the phase and ampli-
tude fluctuations exhibit nonreciprocity at times.

165

Applied Electromagnetic Theory at Frequencies Below 300 kc/s,

A theoretical problem of propagating an electromagnetic pulse via composite
ground and ionospheric waves was solved for propagation in the waveguide
between the ionosphere and the ground, for long wavelengths (over 1000
m). This required the construction of suitable transfer functions for both
the ground wave and the ionospheric wave. The concept of continuous
stratification of the lower ionosphere and arbitrary, constant magnetic
field was introduced into the solution, so that the form of the lower bound-
ary of the ionosphere with respect to altitude could be taken into account
as a profile of electron density-altitude. N(h), and collision frequency-
altitude. v(h). Collision frequencies proportional to the thermal energy
of the gas were introduced into the analysis with the aid of a complex
collision frequencv parameter in the Langevin equation of motion of an
electron gas. This parameter was found to be frequency-dependent and
characterized by three frequencies: o>. w±<oH where /=g)/2it is the frequency
under consideration and fii = ioH f%r is the gyrofrequency of the electrons.

The residue and zonal harmonic methods for the computation of LF.
VLF. and ELF radio fields were extended to take account of an anisotropic
ionosphere. These methods were introduced as a rigorous supplement to
the geometric-optical theory.

Thus, the exact solution to the problem of propagation of terrestrial
radio waves around a sphere having a concentric ionosphere can be repre-
sented theoretically as a notoriously slowly converging series of zonal har-
monics. Nonetheless, the advent of large-scale computers makes this classi-
cal, apparently intractable, solution quite practical at frequencies less than
30 kc /s. The rigorous residue methods which were also developed in con-
siderable detail on the large-scale computer offer a highly convergent repre-
sentation of the exact solution. It is interesting to note, however, that the
zonal harmonics method is still competitive at frequencies less than 30 kc 's.
since the search for residues in complex Riemann surfaces is difficult to
program reliably for a computer over a wide frequency range. Furthermore,
the zonal harmonics were found to be an independent numerical check in
practice, since this method gives the same answers, by definition, as obtained
using the Cauchy residue theorem. A detailed study was made of all ap-
proximations employed to introduce the effects of anisotropv of the ionosphere
into the theorv of propagation: computer programs were devised to calculate
the field under a variety of circumstances.

An extensive program to interpret the Loran-C radio navigation-timing
pulse measurements with the aid of the theory of propagation described
was begun and methods studied for testing various profiles or models of
the lower ionosphere under the variety of specific experimental conditions
offered by Loran-C. Models were proposed for various times of the day
and various latitudes. In general a considerable knowledge of the lower
ionosphere was gained by application of the theory to experiment. Further,
it was found that such combined effort prompted further research to im-
prove the theory of propagation-

166

Optical Communications Studies, A limited study program on laser
systems was initiated to investigate the propagation of coherent optical
(infrared and submillimeter wave) radiation through the atmosphere to
provide information on short-term fading and angular scintillation for
communication channel characterization. A helium-neon cw laser will be
used initially for a radiation source and transmission from Pikes Peak to
Boulder is now being carried on. Microwave and meteorological meas-
urements for this path will be obtained and the laser data will be analyzed
and correlated with the measurements.

UPPER ATMOSPHERE AND SPACE PHYSICS

Knowledge of the atmospheric medium is a prerequisite to the under-
standing of the propagation of radio waves through this medium. This
knowledge is also essential in a host of applications in addition to radio com-
munication. The program of upper atmosphere studies is conducted using
three experimental approaches in addition to theoretical studies. The ex-
perimental approaches are (1) ground-based geophysical observations, (2)
satellite observations, and (3) laboratory experiments simulating atmos-
pher'c processes.

Jicamarca Radar Observatory, At the Jicamarca Radar Observa-
tory, located on the magnetic equator near Lima, Peru, studies are being
made of various features of the equatorial ionosphere with a powerful radar
at 50 Mc/s. Its basic function is to study the distribution of electron
density for heights to 10,000 km or more above the earth's surface by means
of the incoherent scatter technique. Other parameters of the ionosphere,
such as electron and ion temperatures, are also being measured.

It was recently discovered at Jicamarca that ion gyrations, which were
expected to affect the incoherent scatter signal, were not detectable. This
result has now been explained on theoretical grounds. Thus, the use of the
Jicamarca radar as a ground-based mass-spectrometer will now depend upon
other characteristics of the incoherent scatter spectrum.

The Jicamarca radar has been operating at full capability for incoherent
scatter studies since December 1962. Since that time incoherent scatter
observations have been limited to tests aimed at confirming theoretical
predictions of the influence of the ion and electron temperatures. This has
been necessary, inasmuch as some difficulty is experienced in measuring elec-
tron density accurately in regions where more than one ion species is present
in significant concentration. The preliminary tests are nearing completion
and it is hoped that semiroutine measurements of electron density versus
height, as well as ion and electron temperatures versus height, will soon begin.

The extremely high radar sensitivity available at Jicamarca enabled the
detection of radar echoes from Venus when the planet was observable from
Lima during the first week of December 1962. Both short (l/2000th of
a second) and long (3/1000th of a second) pulses were transmitted.
Echoes from the long pulses often were at a level four times the background
noise. Practically no pulse-spreading was observed, indicating that the

714-691 O— 64 12 167

surface of Venus is considerably smoother than that of the moon.

From observations of the synchrotron radio noise emitted by trapped
electrons resulting from the July 9, 1962 nuclear explosion, a fairly accurate
description of the energy distribution of the electrons was made. The decay
rate of the artificial radiation belt was observed and is the subject of con-
tinuing study.

The equatorial electro jet is one of the equatorial phenomena being studied
at Jicamarca. This is a strong daytime current stream flowing in the
ionosphere at a height 100 km above the magnetic equator. Radar echoes
obtained from irregularities in the electro jet led to the theoretical explana-
tion that the irregularities are produced by a "two-stream" plasma instability
in the electro jet current. The theoretical and experimental results are
completely consistent in the electro jet case, and the implication is that the
same interpretation can account for similar irregularities observable in the
aurora. The results obtained at Jicamarca form one of the first instances
in which theoretical predictions regarding plasma irregularities were con-
firmed experimentally with good precision.

"^^*m»mm, jS,

1 '""MIIM'I li II" lliilumml

The 22-acre radar antenna of the Jicamarca Radar Observatory near Lima, Peru,
was recently used for studies of the planet Venus and the equatorial electrojel
in addition to its regular functions in measuring parameters of the ionosphere.
(Seep. 167.)

168

Digital correlator and
control system for the
Jicamarca Radar Ob-
servatory near Lima,
Peru, provides for
more efficient use of
the radar and analyses
of the received signals.
(Seep. 169.)

Digital Control and Correlation System for the Jicamarca Radar
Observatory. The Jicamarca radar is used to measure the characteristics
of the ionization in the ionosphere and exosphere. Since the reflected radar
signals are often very weak, special detection methods must be used to extract
the desired signals from the noise background. A new device for doing this
was recently installed at the radar site. This device, called a digital cor-
relator, is actually an interconnected set of timing and signal-processing
modules which forms a complete control and detection system for the radar.

Individual modules of the system include voltage-to-digital converters,
a magnetic-core buffer, a multiplier, a pulse-height analyzer modified to
serve as a multichannel accumulator, and a variety of pulse-generating and
switching units. The sequence of events occurring in an experiment is de-
termined by a module called a programmed controller, which controls the
sequence in which other modules perform such functions as radar pulsing,
observing the reflected radar signals, storing the received signals, and com-
puting correlation coefficients.

The entire system of digital correlator modules and the radar is electrically
interconnected through a removable plugboard. An experiment can be set
up in a relatively short time by placing a plugboard, which has been pre-
wired to perform the functions of a particular experiment, in the plug-
board receiver. By this means, within a few minutes after an unusual

169

ionospheric or exospheric phenomenon occurs, an experiment designed to
observe that phenomenon can be in operation or an. existing experiment
modified to make special observations. The result of having the correlator
in use is that better, more rapid, and more numerous observations and ex-
periments are made possible.

Studies at Magnetically Conjugate Points. Following the successful
pilot conjugate point experiment conducted during the Antarctic summer
of 1961-62, a more ambitious operation was organized, supported in part
by the National Science Foundation, to run through 1963 and extend into
the IQSY.

The concept of conjugate-point studies is that observations made at
opposite ends of a given line of the geomagnetic field permit the investigation
of geophysical phenomena which are propagated along the field. The pilot
experiment used just one pair of stations and therefore gathered data on
phenomena occurring on just one geomagnetic field-line (L = 4). The new
program includes three conjugate pairs: Antarctic stations South Pole
(L— 13), Byrd (£ = 7%), and Eights (L = 4>) are paired with corresponding
Canadian stations at Frobisher Bay, Great Whale River, and Baie St. Paul.
The data will be obtained from latitudes greater than, equal to, and less than
that of the auroral zone maximum.

A variety of instruments, including the riometer, VLF receiver, micro-
pulsation equipment, and magnetometer, is in use at the conjugate stations.
The wealth of new data being obtained will be applied to test and extend the
preliminary results obtained previously. It is already apparent that many
of the absorption events measured with riometers are of different intensity
in the two hemispheres, and there are indications that significant time delays
exist between some conjugate events. Although many events correlate very
well, some are observed in only one hemisphere. When full data become
available from the Antarctic, a more complete analysis of the occurrence,
structure, scale, and movement of absorption events will be possible. Valu-
able data are being gathered about VLF emissions, both discrete and con-
tinuous. The wide range of techniques now in use will make for interesting
interdisciplinary comparisons.

Continuous Observations of VLF Emissions. VLF emissions have
been observed continuously since May 1961 and recorded continuously at
several locations. Because of the low time resolution of the instrument it
was possible for the first time to pick up VLF pulsations having periods of
20 to 300 seconds. These periods are in the same time range as micropulsa-
tions and some X-ray events; the possible connection between these two
phenomena and VLF events is being studied.

VLF Emissions and Whistlers at Conjugate Points. The Bureau
started its program of systematic observations at magnetically conjugate
points in 1961. Whistlers echoing between the hemispheres were observed
as early as 1956, but only a few observations of VLF emissions at conjugate
points have been reported. The results from the conjugate point stations
reveal several patterns.

170

VLF emission events which last for several minutes to several hours are
seen simultaneously at conjugate points. When these same events are ex-
amined in detail, it is found that the separate discrete emissions which make
up the total event alternate between the hemispheres. This alternance may
be due to echoing of the VLF wave, or re-emission of the wave.

Electron Densities in the Lower Ionosphere, The D-region and its
physical and chemical properties are of interest from the practical viewpoint
because of the disruptive effects the Z)-region can have on long-range radio
transmissions. The D-region is of great scientific interest also because it is
the region where energetic particles of extraterrestrial origin interact with
the atmosphere. However, the Z)-region is at a particularly difficult height
(40 to 90 km) to study directly because the atmospheric density is too great
for satellites to orbit in it and too small to support high-altitude balloons.
Therefore it must be studied by rockets (which remain in the region only
minutes) or by ground-based techniques. The latter have the advantage of
continuous operation.

An observational program was conducted to measure the auroral-zone
absorption of cosmic radio noise as a function of frequency. By means
of refined experimental techniques and the development of a special com-
puter program, it is possible to interpret these data in terms of the height
profile of electron density in the D-region. Such profiles have been deduced
for polar-cap absorption events and for some types of auroral events. The
analysis is continuing, and should provide valuable information about the
physical and chemical processes of the D-region.

This research is supported in part by the Advanced Research Projects
Agency.

Auroral Absorption. Radio propagation in the HF and lower VHF
bands at high latitudes is characterized by the frequent occurrence of strong
absorption which is often extremely variable in both time and space. This
absorption occurs in general association with aurora and magnetic disturb-
ance and has become known as "auroral absorption" to distinguish it from
the less common "polar-cap absorption" associated with the influx of solar
cosmic rays. Auroral absorption displays several mysterious features; a
theoretical investigation of particle bombardment processes in the upper
atmosphere has been started, with the ultimate aim of explaining some of
these features. In particular, the role of high-temperature electrons in
producing some of the observed effects is being considered. When an
electron is freshly produced by ionization, its energy may be several hundred
electron-volts, corresponding to an extremely high effective "temperature."
This energy is eventually lost through collisions with atmospheric atoms and
molecules, but during this process the collision frequency is very high so
that the energetic component of the electrons may contribute appreciably
to radio-wave absorption. A further raising of electron temperature, and
hence collision frequency, may be due to electric fields in the ionosphere;
this point is being investigated.

171

Absolute Calibration of Airglow Photometers. Two problems arise
in connection with the calibration of night airglow photometers: the light
level is near the low end of eye visibility, and the large field of view
customarily used makes it difficult to use point sources of light.

The intercalibration of photometers on a national and international basis
is of particular importance. It is estimated that the spread of uncertainty
among the calibrations of the 28 airglow stations participating in the IGY
is probably contained within ±20 percent. A spread of such magnitude
ruled out the possibility of making detailed studies and interpretations
in a synoptic sense-

The Fritz Peak Observatory set up a calibration laboratory in preparation
for the IQSY. The primary standard is a blackbody which illuminates a
magnesium oxide screen. Secondary portable standards have been de-
veloped, using a mixture of two phosphorescent materials in which C14 has
been embedded. The spectral emission covers the range from the N2+ band
at 3914 A to the red oxygen line at 6300 A. Intercalibration between the
Fritz Peak standards and those of other airglow observers will be encouraged
in the hope that a significant improvement will be achieved during the
IQSY.

Mid-Latitude Red Arcs. The occurrence of so-called mid-latitude red
arcs, well-defined bands of atomic oxygen 6300 A red line emission along
restricted geomagnetic latitudes between the auroral and equatorial zones,
has been observed at various times in the past few years. A promising model
now developed attributes the red arc excitation mechanism to electric fields
present in the ionosphere. The detailed calculations agree with the observed
properties of the mid-latitude red arcs as well as with the accompanying
geophysical manifestations of red arc occurrence. These calculations utilize
techniques previously developed at the Bureau for computing electron energy
distribution functions of atmospheric gases in the presence of electric and
magnetic fields. This model is of great interest as it suggests a connection
between the red arc occurrence and the physics of the magnetosphere where
the electric field is probably generated, possibly by the solar wind impinging
on the earth's magnetic boundary.

Studies of Ionospheric Irregularities. Irregularities in electron den-
sity of the ionosphere can be revealed by study of the periodic fading of
radio signals from artificial satellites and cosmic radio sources. An analysis
of irregularities that vary from 50 to 400 km in the horizontal direction
revealed that they occur mostly at night, show no seasonal variations, and
decrease in density with increasing magnetic activity. They also appear to
be distributed throughout the ionosphere. Observations made simultaneously
at three stations in a line parallel to the satellite path enabled a vertical
cross-section of the ionospheric irregularities to be obtained. Such a profile
is like a "snapshot," because of the high velocity of the satellite.

A satellite scheduled for launch during the latter half of 1963 is to carry
an ionospheric beacon transmitter that will enable a new and more accurate
analysis technique to be used. The accuracy of spaced station observations

172

will be improved, in addition, by equipment being built to utilize a new
receiving technique combined with telemetry to a central station. The re-
sulting vertical profiles should reveal the changes of size and shape of irreg-
ularities with relation to such factors as time of day and magnetic activity,
and perhaps serve as a basis for rejecting or accepting theories of their
origin. An ionospheric beacon transmitter has been designed and is being
procured for another satellite, which will have a highly eccentric orbit so
that the measurement of electron densities far above the ionosphere can be
attempted. All of this work is supported by the National Aeronautics and
Space Administration.

Such irregularities can also be studied by observation of the bending of
radio waves that pass through them. Cosmic radio sources are being ob-
served to analyze this bending in a cooperative experiment using a large
radio telescope, at Clark Lake, Calif., built and maintained by General Dy-
namics/Astronautics. Because the apparent motion of cosmic sources is
but a fraction of that of a satellite, the motion of the irregularities thernselves
is being studied by this technique.

The bending of radio waves caused by small-scale irregularities, 1 to 2 km
in the horizontal direction, produces what are called scintillations in radio
signals. Observations of satellite scintillations verified that the height and
intensity of small-scale irregularities increases to the north and that differ-
ences in geographical distribution are related to sunspot activity. This
work was supported by the United States Air Force.

Theoretical Studies of the Outermost Atmosphere. Plasma thrown
out by the sun and impinging on the earth's magnetic field from time to time
produces magnetic disturbances ("magnetic storms"), precipitation of
energetic particles into the ionosphere, occurrence of auroras, and disturb-
ance of ionospheric radio communication. The mechanisms relating these
phenomena to each other are, however, not yet fully understood. Theoreti-
cal calculations have been made of the interaction of such solar plasma
with the outer portions of the earth's magnetic field. These calculations
show that the boundary region between the plasma and the magnetic field
lies closer to the earth on the night side than was earlier presumed to be
the case, but is farther from the earth in the polar regions than had been
presumed. This latter conclusion is of particular significance in evaluating
mechanisms theorized for the solar plasma reaching and disturbing the
ionosphere. Calculations are continuing on the amount of magnetic field
disturbance associated with variations in the solar plasma, and the con-
sequent displacement of conjugate points, connected by a magnetic field
line on the earth's surface, which have special radio disturbance properties.

Recent satellite measurements greatly extended our knowledge of physical
conditions in the outermost reaches of the earth's magnetic field. They have
shown, in particular, that in the general direction of the sun the magnetic
boundary region is usually found at a distance of 40,000 to 64,000 km from
the earth's surface, and that the trapped particles of the outer Van Allen
belt often extend out as far as this boundary. The behavior of these outer-

173

most trapped particles is believed to be of considerable importance in con-
nection with auroras and magnetic storms • for this reason a theoretical in-
vestigation of their drift motions was carried out recently. It was shown
that particles which become trapped in the outermost part of the geomagnetic
field tend to be concentrated into a relatively narrow belt, because of the
distorted nature of the field, as they drift from the sunward side of the earth
to the dark side. Also, a magnetic storm should have the effect of con-
centrating preexisting trapped particles into similar belts, which can
persist after the storm has ended. Narrow belts of trapped particles of this
type were observed by satellites during magnetic storms. Their existence
may have a direct bearing on the production of the long, narrow arcs of
luminosity often associated with the aurora.

Cyclotron Resonance in Slightly Ionized Gases. A detailed anal-
ysis of the line shape and width of electron cyclotron resonance absorption has
been carried out. At cyclotron resonance, i.e., the gyration frequency of an
electron in a magnetic field, the cyclotron orbits in a weakly ionized gas are
interrupted by electron-neutral collisions, thereby determining the absorp-
tion-line width and shape. Analysis of the width and shape is quite com-
plicated for many real gases due to the velocity dependence of the electron-
neutral elastic collision cross section.

The problem has been solved for various analytical representations of the
velocity-dependent cross sections using various electron energy distribution
functions. The problem was also solved for argon and nitrogen, using
experimentally determined cross sections and a Maxwellian electron dis-
tribution. The extreme importance certain minor impurities could have on
band shape was demonstrated theoretically.

Space Resolved Afterglows. Studies of the space resolved "after-
glow" in a fast-flowing helium discharge system were carried out by means of
emission and absorption spectroscopy. The afterglow technique is being
developed because of its possible use in studying chemical and electronic
reactions where the reactants (and electrons) are thermalized at essentially
room temperature. In the helium case the afterglow shows a very high
molecular-to-atomic emission intensity ratio relative to an active discharge,
a phenomenon as yet not understood. The density of both singlet and trip-
let metastable helium atoms was found to increase somewhat in the helium
afterglow region. The diagnosis of the helium afterglow is being extended
and other systems are being investigated by the flowing afterglow technique.

Infrared Spectra of Charge Transfer Complexes. A comprehen-
sive and novel theory of the infrared spectra of weak charge transfer com-
plexes was developed. These complexes are formed by transfer of electrons
from donors to acceptors; it was shown that the infrared absorption character-
istic of such a complex must be due to variation in the charge transfer.
This variation is a consequence of molecular vibration. Two specific
mechanisms are proposed for the variation and selection rules derived. The
large amount of data available on aromatic-halogen complexes is well ex-
plained by this theory. A solution was proposed to a longstanding ambigu-

174

ity concerning the geometry of benzene-halogen complexes. The geometry
is of great significance for the theoretical understanding of the quantum
mechanical molecular description of such compounds.

Infrared Spectroscopy of the Atmosphere. The Bureau's Consult-
ant in Physics of the Atmosphere conducted a continuing study of the atmos-
phere by means of spectroscopic observations. In order to compute the
transmission of infrared radiation through the earth's atmosphere it is neces-
sary to know the atmospheric spectrum in absolute detail Atmospheric trans-
mission is primarily dependent on absorption and re-emission by water
vapor, carbon dioxide, and ozone. The computation of atmospheric trans-
mission was accomplished by a computer, using as input data the positions,
experimentally known strengths, and half-widths of 4400 specific lines for
transmission through water vapor. The 3.5/x (2857 cm"1) to 2.25/x (4444
cm-1) portion of the spectrum used falls within the nonvisible infrared
region.

The transmission of the atmosphere is computed from the line positions,
strengths, and half-widths, using Beer's Law and a Lorentz line-shape pro-
file. The absorption is computed at any given frequency as the sum of the
wing absorption of all the lines and the profile structure of an individual
line if the frequency position is near a line center. These theoretical ab-
sorption spectra are then degraded, using a slit function, in order to compute
spectra which are comparable to observed spectra. Comparisons with
high-altitude spectra obtained from aircraft by the Canadians and by the
British give excellent agreement with every detail in the water vapor spectrum.

An atlas of computed spectra for the 2.7 /x water vapor transmission has
been prepared. The absorption lines due to water vapor in the 1.1-, 1.4-,
1.9-, and 6.3- fx bands are being compiled. The positions, strengths, and
half-widths of the C02 absorption lines are also under preparation. This
theoretical analysis is being conducted under the sponsorship of the Ad-
vanced Research Projects Agency. The results of the calculations will be
applied to atmospheric radiative transfer problems.

ELECTROMAGNETIC RESEARCH

A number of theoretical studies conducted by the Consultant on Radio
Wave Propagation fall loosely into the category of electromagnetic research.
Supported by the Bureau, the Air Force Cambridge Research Laboratories,
and the Department of Defense Advanced Research Projects Agency, these
seemingly unrelated studies used methods having much in common- Some
of the accomplishments in this area during Fiscal Year 1963 are described
below.

Resonant Characteristics of a Corrugated Sphere. The radiation
from a radial electric dipole on the surface of a corrugated sphere was
examined. It was shown that the power radiated in a given mode depends
critically on the surface reactance and the circumference of the sphere. In
fact, for certain values of these parameters, particular modes are strongly
excited and contain most of the power. Such a structure can be regarded

175

as an external resonator having resonant characteristics that are a function
of the refractive index of the surrounding medium. This opens the possi-
bility that a surface-wave spherical resonator may have important applica-
tions to refractometry.

Influence of a Sector Ground Screen on the Field of a Vertical
Antenna. The field of a short vertical antenna on a homogeneous ground
was shown to be modified by the presence of a metallic screen in the form
of a circular disk and a concentric sector. The modification of the field
was expressed in the form of surface integrals over the disk and the sector.
Extensive numerical results were obtained for these basic integrals.

The Theory of an Antenna Over an Inhomogeneous Ground
Plane. An antenna over a flat ground plane, characterized by a variable
surface impedance, was considered theoretically. The problem was formu-
lated in terms of the mutual impedance between two vertical dipoles. The
ground screen was taken to be in the combined form of a circular disk and
a concentric sector. An approximate solution of the problem was obtained
and the results were compared with previous investigations of closely
related work.

Curves for Ground~wave Propagation Over Mixed Land and Sea
Paths. Specific numerical results were obtained for ground-wave propaga-
tion over paths part of which are over sea and part over land. The problem
is idealized to the extent that the earth is a smooth, spherical surface. The
method is based on a previous formulation in terms of mutual impedance
between two vertical electric dipoles of an inhomogeneous spherical earth.
Amplitude and phase of the ground wave were given for various combina-
tions of the following parameters: frequency 1000, 100, and 20 kc/s; land
conductivities 100 and 10 mmhos/ meter; and a sea conductivity of 4 mhos/
meter. Most of the curves exhibit the well-known recovery effect which
occurs beyond the coastline for propagation from land towards the sea.

Wave Propagation Around a Curved Boundary Containing an
Obstacle. The field of an electric dipole on a smooth spherical ori cylin-
drical surface containing a localized obstruction was calculated- An approx-
imate solution was obtained by combining the rigorous theory of diffraction
by a sphere and the approximate Kirchhoff diffraction theory for black
screens. The application to ground-wave propagation over mountains was
demonstrated.

Oblique Propagation of Radio Waves Across a Coastline. The
theory of mixed-path groundwave propagation was extended to cover oblique
incidence at a straight coastline. To allow for a varying water depth, the
surface impedance was allowed to change gradually from sea to land. ' The
resulting two-dimensional integral equation was solved by a perturbation
method and the solutions for an abrupt coastline and other idealized situ-
ations were obtained as special cases. The apparent field singularities which
emerged in the limiting cases were shown to have a real physical significance.
Using an approximate boundary condition, the influence of a gradual eleva-
tion change at the coastline was considered also.

176

Guided Electromagnetic Waves in the Earth's Crust, A natural
waveguide for electromagnetic waves may exist in the earth's crust. The
attenuation in such a guide was calculated for an idealized model under
more or less optimum conditions. The results obtained by choosing certain
dimensionless parameters may have rather broad applications to problems
of this type.

Electromagnetic Scattering From a Sphere. The generalization of
the Lorenz-Mie theory for scattering from a homogeneous sphere to a radially
inhomogeneous sphere was carried out. In this case the scatterer consists
of a spherical body with any number of homogeneous or inhomogeneous
concentric regions. The treatment makes use of the analogy with nonuniform
transmission line theory. The results have application to radar techniques
for investigating ionized clouds.

VLF Radio Propagation in an Anisotropic Ionosphere* The the-
ory of the propagation of electromagnetic waves in the space between a
spherical conducting earth and a concentric ionospheric reflecting layer was
treated a novel manner. The problem was idealized to the extent that the
tangential field components at the boundaries of this spherical waveguide
are related in a prescribed way. At the ground, the relation involves a scalar
surface impedance, while it was found necessary to employ a reflection
coefficient or surface impedance for the ionosphere in the form of a matrix.
A solution was sought for the total field produced by a vertical electric
dipole and explicit results were obtained by assuming azimuthal symmetry.
A representation in terms of guided waves was obtained by applying the
Watson transformation and used to obtain specific results.

Excitation of Modes at Very Low Frequency, The concept of VLF
radio waves being propagated between the earth and the ionosphere in the
manner of a waveguide has proved very useful. As much neglected aspect
of the subject, however, is the manner in which the modes of propagation are
excited. A valid analysis requires that the earth's curvature and the grazing
nature of the modes be properly accounted for. An expression for the
excitation factor was obtained by using Airy integral or third-order approx-
imations for the spherical wave functions. It was indicated that the modes
of very low attenuation may be accompanied by excitation factors much less
than unity. There is evidence of this phenomenon in some old experimental
data at frequencies of the order of 25 kc/s. A mode of this type can be
imagined as becoming "detached" from the lower boundary of the earth-
ionosphere waveguide. In this situation, the height-gain functions increase
with height and the modal characteristics depend only slightly on ground
characteristics.

Height Gain for VLF Radio Waves. The height dependence of the
field strength of VLF radio waves was considered. Using previously de-
veloped theory, the height-gain function of the first two modes was calculated
in terms of Airy functions of complex argument. For frequencies of the
order of 25 kc/s, the height-gain function reaches a maximum value at a
height of about 40 km, for a reflecting layer at about 70 km. The form of

177

the height-gain function was also shown to be dependent on the finite con-
ductivity of the ground. An experimental curve, for 18.0 kc/s, based on a
rocket measurement shows some agreement with the theory.

Characteristics of an Inhomogeneous D-layer at VLF. The verti-
cally polarized reflection coefficient from a horizontally graded D-layer was
calculated, using wave methods. The exponential conductivity profile was
given special attention, as being representative of the daytime quiescent
ionosphere. The results showed that the gradient of the lower ionosphere is
most important in determining the magnitude of the reflection coefficient at
highly oblique incidence. However, the functional relationship between the
gradient and the reflection characteristics is not simple; a sharp gradient,
for example, is not always associated with high reflection coefficients at VLF,
contrary to repeated statements in the literature. The results were also ex-
tended to a study of the relation between attenuation and phase velocity of
the waveguide modes when the ionosphere is not sharply bounded.

The influence of idealized perturbations on the undisturbed profiles was
also considered- The results demonstrated, among other things, what levels
in the lower ionosphere are most effective in VLF propagation. While the
general results were complicated, some important basic principles concerning
the reflection coefficient were established.

Propagation in a Nonuniform Earth-Ionosphere Waveguide. An
approximate theory for propagation of electromagnetic waves in a curved
waveguide of variable width was developed at the Bureau, based on a direct
application of the Lorentz reciprocity theorem. The final result is in the
form of a line integral which involves the profile of the ionospheric reflecting
layer as a function of the horizontal distance. By making a number of
simplifications, valid for small perturbations, the physical consequences of
nonuniform reflecting height were made evident. It was indicated in par-
ticular that perturbations at the reflecting level introduce higher-order modes
in the waveguide. The results have application to the theory of VLF radio
wave propagation when the ionospheric heights are not constant along the
path.

Microwave Models for VLF Propagation. Work has continued on
the study of microwave models of VLF radio propagation, in collaboration
with the University of Colorado. The rectangular waveguide used as a
model has approximately the same width in wavelengths, measured at 9Gc/s,
as the height of the ionosphere, at 15 kc/s. The waveguide has a modal
equation approximately the same as that of the earth-ionosphere waveguide
at VLF frequencies. Perturbations in the walls of the waveguide affect
propagation through it in a manner similar to that in which ionospheric
perturbations affect propagation through the earth-ionosphere waveguide.

Experimental studies were made of propagation in the waveguide with
several different wall perturbations. It was found that wall perturbation
causes the conversion of substantial amounts of energy from one of the
propagating modes to others, as suggested by theory. Since there are 15
propagation modes in the waveguide, the effects of the perturbation are

178

noticeable at great distances from it. Furthermore, it was found that the
amount of energy converted to various propagating modes is critically de-
pendent upon the size and shape of the perturbation. Because of this fact,
it should be possible to determine the approximate size and shape of iono-
spheric perturbations from field measurements at the surface of the earth.

Theory of Magnet otelluric Fields. A general theory of magneto-
telluric fields was developed in connection with the combined analyses of the
geomagnetic and the telluric (earth current) fields on the surface of the
earth. The usual objective of such investigations is to obtain information
about the earth's crustal' layers, but in this case it is desired to understand
something about the source of the fields. Possible source mechanisms were
reviewed and detailed study of previous work on the theory of magnetotelluric
interpretation was carried out. A number of three-layer interpretation
curves were prepared, which also can be applied to radio propagation over
a stratified conductor-

2.3.5. CRYOGENIC ENGINEERING

The cryogenic engineering activities, centered at the Boulder Laboratories,
provide information needed for practical applications of materials, systems,
and techniques at very low temperatures. Missiles and space programs rely-
ing on cryogenic liquids as propellants, and scientific programs requiring ex-
tremely low temperatures, have increased the demand for information from
the cryogenic engineering laboratories. To cooperate in these activities, the
Bureau conducts research to determine the physical properties of materials
at cryogenic temperatures and develops methods for measuring these
properties and the characteristics of cryogenic systems. In addition, it
maintains a national Cryogenic Data Center where information on cryogenic
engineering is collected and organized for use by other Government agen-
cies, industry, and the public.

Dielectric Behavior of Dense Parahydrogen. Urgent demands by
design engineers for data on parahydrogen have resulted in extensive meas-
urements by the Bureau with support from the National Aeronautics and
Space Administration (NASA). Such investigations involve studies of the
dielectric constant of parahydrogen.

The dielectric constant of a nondipolar fluid may be represented as a
function of density with good accuracy by the classical formula of Clausius-
Mossotti. However, deviations in dielectric constant, caused by the effects
of transient dipoles, permanent multip6le moments, if present, and changes in
the molecular polarizability due to interactions with close neighbors, may
occur.

The theories of such effects have developed rapidly in the past decade but
are not yet quantitatively accurate. Also, experimental data accurate enough
to clearly show these small effects are scarce. Hydrogen is not a particularly
good substance in which to study them, since neither its reduced polariza-
bility nor its electric quadrople moment is very large. However, the avail-

179

ability of accurate density data recently determined by the Bureau offsets
this disadvantage. Knowing the dielectric constant accurately is important
to scientists and engineers because many instrumental techniques for deter-
mining density, liquid level, and quality of a fluid depend on capacitance
measurements.

Polarization isotherms for hydrogen have been determined from 20 to
90 °K at pressures up to 30 atm covering both the liquid and gaseous states.
These isotherms rise with increasing density to a maximum, and then fall.
This behavior is in qualitative accord with the prediction of theory and the
limited experimental data on related substances. These are the first data on
hydrogen of sufficient precision to show departures from Clausius-Mossotti
behavior.

Superconductivity, The Bureau, in conjunction with the Atomic En-
ergy Commission (AEC), is investigating the energy gap in superconducting
thin films as a function of film thickness, temperature, and magnetic field.
Critical fields of tin and lead films have been determined by measuring the
magnetic field at which the energy gap vanishes. Analysis of the data in

Cryostat and magnet
used in investigating
superconductivity in
thin films. (See
p. 180.)

180

terms of the Bardeen, Cooper, Schrieffer (BCS) theory of superconductivity
is aided by computer techniques. Magnetization measurements on cold
drawn niobium wire can best be interpreted in terms of the Ginzburg-Landau,
Abrikosov, Gor'kov (GLAG) theory of superconductivity. Mathematical
research extending this theory affords better interpretation of the results.

Magnetic Properties in Silicon Steel, Bureau scientists are employ-
ing a magneto-optic apparatus to observe the domain structure in silicon steels
as small stresses or changes in temperature occur. Unlike the powder pat-
tern technique, this apparatus reveals the complete surface domain structure
without regard to the type of domain wall. The behavior under stress of a
new pattern, termed the "chevron," has been noted.

Low-Temperature Seals, A program concerned with improving low-
temperature seals is being carried out by the Bureau in cooperation with the
U.S. Air Force. In these studies the thermal expansion properties and brittle
transition temperatures of about 40 elastomers, representing eight basic
polymer types, were measured. These results, combined with resilience and
differential thermal analysis measurements, are being used to predict the
usefulness of these materials as low-temperature seals.

Cryogenic Literature Service, The Cryogenic Data Center's docu-
mentation unit searches the world literature for technical information per-
tinent to the cryogenic engineering field and promotes an awareness of such
literature to the Bureau staff and the cryogenic industry. Some 4100 new
references were coded and entered into the Center's storage and retrieval
system. Special attention was still given to low-temperature data on the
"properties of fluids" and "properties of solids" categories ; thus 1500 of the
new entries were in these categories. The versatility of the computer search
program was increased when the program was converted to suit a new com-
puter. A number of extensive bibliographies on properties of materials was
compiled during the year.

More than 2500 documents were procured from world sources for the
Bureau staff. About 600 of these were in microform, which is less costly
and often of better quality than full size copy. The staff distributed an
estimated 20,000 items of NBS literature in response to some 1500 requests.
Announcements of available material and services are sent, at three-month
intervals, to approximately 4000 persons and institutions on the Center's
mailing list. Arrangements are also being made to provide the NBS
material in microform, thus greatly reducing reproduction cost and facilitat-
ing handling. Use of technical literature in this form is becoming more
popular now that good readers and printers are available at reasonable
prices.

The documentation unit works closely with the Center's evaluation unit in
providing literature-procurement services and in bibliography retrieval.
The evaluation unit is not only a primary user of these services, but is also a
major contributor of information on cryogenic literature from their compila-
tion programs and the associated literature searching on selected topics.

181

Thermo physical Properties of Cryogenic Materials. With support
from NASA, the Cryogenic Data Center is evaluating and compiling data on
the thermophysical properties of materials from the scientific literature. The
objective is to publish authoritative and comprehensive tables and graphs
of data in a form convenient to scientists and engineers studying cryogenic
phenomena and designing cryogenic systems. If the desired data to complete
a table are not available from the literature, values are computed from cor-
relations based on theory and the properties of related materials.

Considerable progress has been made in compiling thermodynamic data
on the properties of neon and carbon monoxide. The resulting tables, to-
gether with property charts and a description of computational methods, will
be published by the Bureau. A temperature-entropy' diagram for nitrogen
has also been constructed and is now available. Interim reports with pre-
liminary tables for oxygen and argon are being prepared for use while
further evaluations of these elements are in progress. Collections of data on
the surface tension values and dielectric constants of cryogenic fluids and the
electrical resistivity values for pure metals are also being evaluated.

In other work, extensive bibliographies on the thermophysical properties
of fluorine and on the thermal conductivity of cryogenic liquids were com-
pleted during the year. Bibliographies on the properties of argon and on
the saturation properties (i.e., vapor pressure, saturation densities, latent
heats, specific heats at constant saturation) of the cryogenic fluids are nearly
complete.

The thermodynamic properties of cryogenic fluids at low pressures have
been computed at the Georgia Institute of Technology under an NBS contract,
as a part of this compilation program. During the past year reports on this
activity, which include extensive tabulations of data, have been issued on
the vapor pressure and heats of vaporization and sublimation of methane,
nitrogen, and fluorine.

Fluid Flow and Heat Transfer Phenomena. Information on fluid
flow and heat transfer phenomena are necessary to provide design information
in cryogenic systems. One specific problem occurs in cryogenic liquid-vapor
flow where the mass rate of flow is often limited by choking in a restriction
such as a valve or at the exit of a system. This choking two-phase flow dif-
fers from similar single phase problems and often the choking flow velocity
is reduced by an order of magnitude or more. Idealized solutions for pre-
dicting the upper and lower limits of choking two-phase flow for cryogenic
fluids have been completed. These solutions are intended for use as design
guides and as computational aids for research projects.

The characteristics of a number of pieces of equipment, particularly pumps,
are markedly changed if vapor is formed in a flowing cryogenic liquid.
Studies have been underway to detennine the nucleation or bubble-forming
characteristics of cryogenic liquids. These studies show that in static systems
the pressure may be reduced below the vapor pressure before the vapor
phase occurs.

Equipment exposed to the atmosphere (such as vaporizers, uninsulated

182

Liquid hydrogen cryostafc for
testing fluid level sensors.
Tests are made of such char-
acteristics as repeatability and
response time. (See p. 183.)

cryogenic fluid transfer lines, air dryers, and missile tanks) has very low-
temperature surfaces. A study concerned with the characteristics of frost
formation and heat and mass transfer on such surfaces is nearing completion.

Studies of fluid flow and heat transfer processes occurring during the
cooldown of cryogenic transfer lines are underway. Experimental data for
liquid nitrogen flow in an insulated, transfer line have been obtained. Cool-
down times vary with initial flow conditions, and maximum surge pressures
measured in the system were found to be up to three times the initial driving
pressures. Analytical work to provide design data for the cooldown process
is in progress.

Cryogenic Instrumentation. A study of cryogenic instrumentation
is being conducted with support from NASA. Transducers for accurate, pre-
cise measurements of the liquid level, temperature, and mass flow of cryo-
genic fluids are being investigated. Both theoretical and experimental re-
search are being conducted to define and extend the use of the predominate
intensive coefficients for measurements.

714-691 0—64-

183

A state-of-the-art evaluation of commercial liquid-level point sensors for
hydrogen involving 18 manufacturers has been completed. Some of the
devices tested indicated liquid hydrogen level repeatability within 0.020 in.
Response times on some types were approximately 5 and 10 msec, respectively,
as the devices were immersed and withdrawn from liquid hydrogen. Types
of devices tested included resistive, capacitive, optical, piezoelectric, magneto-
strictive, and vibratory (low-frequency paddle).

Cryopropellanl Research, A study of the bulk density of boiling
liquid oxygen, stimulated by the needs of rocket propulsion programs, has
been completed by the Bureau with support from NASA. Satisfactory agree-
ment was obtained between the theoretical analysis and the experimental
research to determine the mass and volume of propellant aboard a vehicle at

Investigation of cryopropellant freezing phenomena. Propellants leaking or
venting in low-pressure environments may cause solids to form in critical
regions, resulting in possible failure of space vehicle propellant systems. (See
p. 184.)

184

any time. The theoretical analysis was also applied to boiling liquid hydro-
gen. Analytical results demonstrate the ratio of bulk density to saturated
liquid density to be a function of a parameter involving saturated liquid
properties and tank geometry. For liquid oxygen, the change in bulk
density is not large — approaching a maximum value of three percent at the
extreme conditions of large heat input rates, tall liquid columns, and small
diameters. For low-density, low latent heat (per unit volume) liquid such
as liquid hydrogen, the predicted change in bulk density is much greater.

In other work, problems in utilizing cryogenic propellants at high altitudes
are being investigated. One such problem is associated with the formation
of solids in critical areas. These formations can obstruct or retard flow
and thereby cause a malfunction in the propellant system of a space vehicle.
Also of interest is the effect of micrometeorite punctures in the propellant
storage system. Either a free or obstructed flow of propellant to the ambient
low-pressure region in such cases would result, depending upon the solid
formation (plugging) characteristics of the situation. Both qualitative and
quantitative studies are now in progress on those variables which may in-
fluence the solid formation in cryopropellants — particularly in liquid hydro-
gen and liquid oxygen. Experimental information obtained thus far
indicates that cryopropellant flow may be closely predicted by conventional
adiabatic incompressible fluid flow equations utilizing empirical (handbook)
orifice-flow coefficient data.

Refrigeration Processes. The development of methods for providing
refrigeration in the cryogenic temperature range is important to military,
industrial, and research programs. Computational work, aided by a digital
computer, is being performed on classical refrigeration processes. Correla-
tions, resulting from the study, will make it possible to design composite
refrigeration systems with increased operating efficiency. With the partial
support of the Atomic Energy Commission, the Bureau is conducting a
theoretical study of feasible cycles adaptable to the temperature region 1.5
to 30 °K.

Expansion engines are vital components of refrigeration systems. The
development of a miniature high-speed turbine expander supported by hydro-
static (externally pressurized), helium gas-lubricated bearings is continuing.
An improved design of expander nozzles and rotors has given a 0.3116-in.-
diam turbine rotor speeds of 11,000 revolutions per second at an adiabatic
efficiency of 80 percent when operating with a pressure ratio of 4:1.

Consultation and Advisory Services. The Bureau provides cryogenic
engineering consultation and advisory services in several areas. Other
Government agencies utilize the broad experience of NBS personnel in de-
signing equipment and handling cryogenic fluids. For example, the Bureau
is providing consultation and advisory services to the Air Force Cambridge
Research Laboratory in connection with cryogenic problems encountered in
developing a cryogenic "whole air" sampler. The sampler, carried by
rockets into the upper atmosphere, uses liquid hydrogen to condense the air

185

sample as it is being collected. This means for sampling the atmosphere
promises to be much more effective than equipment currently in use.

Assistance is being given to Projects Centaur, Rover, and NERVA under
the sponsorship of National Aeronautics and Space Administration. The
Centaur, first space vehicle to use liquid hydrogen as a propellant, will be
followed by the nuclear rocket programs, Rover and NERVA, that are
planning more extensive use of liquid hydrogen. The physical properties
of hydrogen are sufficiently different from other propellants to present many
new problems to the industry. Principal contractors of these programs
receive Bureau support in the areas of ground support equipment, insulation,
instrumentation, thermodynamics, and plans, specifications, and equipment
review.

In cooperation with the Central European Organization for Nuclear Re-
search (CERN), Geneva, Switzerland, NBS personnel tested and evaluated
a hydrogen liquefier at the Bureau facilities-

Under the sponsorship of the Atomic Energy Commission, the Bureau as-
sisted in evaluating air dielectric coaxial cables as cryogenic transfer lines.
Such high-frequency electrical transmission cables having suitable physical
configuration were found to be useful for transferring certain cryogenic
fluids and could substantially reduce initial investments for transferring
these fluids.

Liquefied and Purified Gases. All of the liquefied gases used at the
Boulder Laboratories are now procured from commercial sources ; none has
had to be produced with the NBS facilities for more than a year. The helium
liquefier is still being maintained in a ready standby condition, however,
because of some uncertainties in commercial transportation delivery. The
liquid hydrogen plant is still being used to repurify hydrogen gas collected
from liquid evaporation and for research and development on cryogenic
systems. The liquid nitrogen plants have been listed as surplus and are
available for transfer to another agency.

The approximate amounts of liquefied gas procured this year were as
follows: 830 liters of helium; 50,000 liters of hydrogen; and 370,000 liters
of nitrogen. Most of these liquids were distributed to laboratory projects;
however, small amounts of liquefied and pure gases were distributed to some
12 laboratories outside the Bureau which had no other convenient source of
supply. More than 100,000 scf of hydrogen gas were collected and repurified
for laboratory use; no hydrogen gas was purchased for this purpose. About
60,000 scf of nitrogen gas were used during the year, essentially all of which
was provided by the vaporization of liquid nitrogen.

2.3.6. BUILDING RESEARCH

The Bureau conducts research in chemistry, physics, and engineering to
obtain data on the properties and performance of building materials, struc-
tures, and equipment; and develops methods for testing materials, mech-
anisms, and structures. The Bureau assists other laboratories engaged in
building research by devising techniques for accurate measurements, develop-

186

ing and supplying calibrated laboratory reference standards, and participating
in interlaboratory programs for checking measurement precision. Coopera-
tion with public and private agencies to develop and improve code and
standards for safe and effective use of materials and equipment is also an
important part of the overall program.

A consultant service is maintained to advise Government agencies on build-
ing problems, and to aid public and private organizations in formulating
specifications and national standards that concern the building industry.
For example, the U.S. Air Force Academy consulted the Bureau before
choosing sealants suitable for the joints between aluminum-faced roof ele-
ments of the Academy Chapel; and the National Gallery of Art called upon
the Bureau to help select a sealant for glass skylights.

Explosions on marine tankers after shipments of fuels and chemicals have
prompted the Secretary of the Treasury to appoint a "Special Committee on
Tanker Hazards." An NBS staif member serves on this committee which is
studying the hazards of vapors associated with the cargoes in the ullage and
other spaces in such vessels.

During the year, members of the staff conducted a symposium on Fire
Test Methods for the Committee on Fire Research of the National Academy
of Sciences — National Research Council. Another Symposium on Measure-
ment of Thermal Radiation Properties of Solids was sponsored jointly
by the Bureau, the Air Force, and the National Aeronautics and Space
Administration.

Building Codes and Safety Standards. In performing its responsi-
bility as the sole sponsor, the Bureau reorganized the Committee on Building
Code Requirements for Masonry of the American Standards Association
(ASA) and added 12 new members. The Committee began revising the
American Standard Building Code Requirements for Masonry about midyear
when a subcommittee prepared and reviewed a first draft, based upon re-
sponses to a widely circulated request for suggestions.

The Bureau, as sole sponsor, reactivated and increased the membership of
ASA's committee on Building Code Requirements for Minimum Design
Loads in Buildings. The seven organizations and nine general-interest
members added to this Committee are all exceptionally well qualified to
contribute to the Committee's work.

Through membership on committees operating under procedures of the
ASA, the Bureau assisted in (1) revising the National Electrical Code, (2)
developing plumbing, heating, and electrical standards for mobile homes
and travel trailers, (3) preparing a proposed revision to the National Plumb-
ing Code, (4) reviewing existing standards for plumbing materials, (5)
preparing a proposed revision to the Safety Code for Elevators, and (6) pre-
paring proposed safety codes for mechanized parking garage equipment,
cranes, derricks, and hoists; and powered platforms.

Creep and Shrinkage of Structural Lightweight Concretes, Dur-
ing the past three years, the Bureau, in cooperation with the Expanded
Shale, Clay, and Slate Institute, has conducted experiments on the creep and

187

Measurement of creep
in cylinders of light-
weight concrete sub-
jected to a constant
stress of 2000 psi.
Creep is important be-
cause it affects the
long-term deflections
in reinforced concrete
structures. (See p.
187.)

shrinkage of lightweight aggregate concretes and has compared the results
with concretes containing normal weight aggregates.

Although creep values among individual aggregates varied a great deal,
the magnitude of creep for a concrete made with a given aggregate was found
to vary approximately linearly with the ratio of applied stress to the strength
of concrete at the time of initial loading. The investigation indicated that
both creep and drying shrinkage values were slightly higher for lightweight
concrete and that the 2-year creep of a concrete can be estimated with an
acceptable accuracy from observations made after 90 days of loading.

Joint Sealants for Building Components. With the support of the
Army, Navy, and Air Force, the Bureau maintains a joint sealant laboratory
where scientific test data on the properties and performance of sealant
formulations are obtained. These data form the basis of standard test
procedures which are incorporated in both Federal and American Society
for Testing and Materials (ASTM) Specifications. Both specifications serve
as guides for architects, builders, and engineers in selecting suitable sealants.
Draft specifications for the one-component, chemically curing type (poly-
sulfide, silicone, urethane, etc.) and the one-component, volatile curing type
(butyl, chloro-sulfonated polyethylene, acrylic, etc.) are being prepared.
Also, as a result of recent research and field experience, revisions are being
made in the specifications for two-component rubber base sealants and one-
part oil and resin base types.

Waterproofing Underground Structures. The Army, Navy, and
Air Force support a Bureau program in which materials potentially useful
for waterproofing underground structures are investigated- The immediate

188

need for such information is related to missile sites, but such knowledge will
be applicable to other underground structures, including basements of houses,
and, in part, to roofs.

A device, built to simulate the damage that could occur from a backfilling
operation and from high water pressure, was employed to test a number of
materials. The test results were compared with various physical tests per-
formed on the material such as tensile strength, bursting strength, puncture
resistance, and tear strength. Although there was considerable agreement
in the results, there were exceptions to any single test or combination of tests.
The laboratory work indicates that the large number of plies usually specified
for waterproofing deep underground structures can be reduced.

Colloidal Nature of Asphalts. Recent experimental work at the Bu-
reau shows that the asphaltene fraction (the dispersed phase) of asphalt
carries a charge, as proposed in the colloidal theory of asphalt.

In this work the asphaltenes were separated from the asphalt, suspended
in nitromethane, and introduced into a microelectrophoresis cell. Aided by
a microscope and a calibrated grid, the rate of movement of the particle at
a selected potential was determined. The electrophoretic mobility of the
asphaltenes was then calculated.

Attempts to correlate electrophoretic mobility with the weathering dura-
bility of six asphalts, as determined by other means, were unsuccessful. The
charge on the asphaltenes and, consequently, polar bonding forces probably
play a minor role in asphalt durability.

Photo-oxidation Products in Plastics Identified. A sensitive col-
orimetric method for measuring photo-oxidation in fiberglass-reinforced
polyester plastics was applied, with modifications, to poly (vinyl chloride),
poly (methyl methacrylate), and cellulose acetate-butyrate plastics systems.
Weathered specimens, when treated with simple phenylenediamines, develop
a pronounced color. Spectroscopic analysis of acetic acid solutions of exposed
poly (methyl methacrylate-diamine) and cellulose acetate-butyrate-diamine
reaction products showed distinct absorbance peaks in the ultraviolet and
visible regions, respectively. Similarly, certain pure organic compounds
were found to react with diamines to produce colored products with absorb-
ance peaks in the visible and ultraviolet regions. Photo-oxidation products
could then be identified by matching the absorbance peaks.

Fluid Dynamics of Plumbing. The writers of plumbing codes and
equipment standards, as well as design engineers, lack specific information
on the complex fluid dynamics of plumbing needed to determine safe, eco-
nomic pipe sizes, configurations, and designs.

A current study, sponsored by the National Association of Home Builders,
indicates the possibility for reducing costs and increasing the flexibility of
plumbing fixture arrangements by designs which minimize the need for vent
piping.

Test Methods for Air-Conditioning Units. Laboratory data on the
cooling capacity of air-conditioning units by three different test methods
were used for analyzing the probable measurement errors in several test

189

procedures. The three kinds of capacity measurements agreed within 4 per-
cent in a large majority of the tests. The investigation indicated the need
for better wet-bulb and refrigerant flowmeter instrumentation as well as for
more data on air mixing techniques and heat-of-mixing of various refrig-
erants and oil.

Test Methods for Refrigerated Trucks. Laboratory investigations
leading to the development of a testing and rating method for refrigerated
trucks were carried out under the joint sponsorship of the U.S. Department
of Agriculture, the Truck-Body and Equipment Association, and the Bureau.
An apparatus for simulating the effect of solar radiation on the cooling load
of stationary refrigerated trucks was designed and constructed. Prototype
vehicles of several designs, used to study the effect of solar radiation, and
of air, moisture, and heat transmission through the body, showed that air
and moisture transmission differs significantly for different constructions.
Such studies also show that the effect of solar radiation can be satisfactorily
accounted for by a correction factor applied to the steady-state heat transfer
calculation.

Criteria for Heating and Air-Conditioning Duets. Upon comple-
tion of a study sponsored by the Federal Housing Administration, the Bureau
recommended test procedures for evaluating the resistance of heating and
air-conditioning ducts to mold growth, odor emission, deformation at high
humidity and high temperature, bending and crushing deformation, impact
resistance, erosion, airtightness, and resistance to rupture or collapse from
internal pressure. The investigation also provided information on the char-
acteristics of selected ducts made of cement asbestos, glass fiber, paper
laminate, and metal. Flame-spread characteristics of ducts are being inves-
tigated separately at another laboratory.

Thermal Emittance of Ceramic Oxides. As a class, the ceramic
oxides have high melting temperatures and good chemical stability when
heated in air. These properties make them useful for such applications as
furnace linings, fire barriers, re-entry nose cones, and as construction mate-
rials for inboard power supplies in space vehicles. However, for these
materials to be used with maximum advantage, their high-temperature ther-
mophysical properties must be known; one of the more important of these
properties is the thermal emissivity.

Recently, at the request of the National Aeronautics and Space Administra-
tion (NASA), the Bureau designed and constructed equipment for measur-
ing normal spectral emittance of ceramic oxides in the 1 to 15 micron (/*)
range and at temperatures up to 1800 °K. In this equipment, specimens in
the form of hollow cylinders are rotated in a furnace cavity to reduce the
temperature gradient existing between the inside and the outside of the
specimen. The ratio of the energy emitted by the specimen to that emitted
by a blackbody furnace at the same temperature is a measure of the thermal
emittance, and is automatically recorded by a double-beam spectrometer
over the range of ii. to 15

190

Automation of Thermal Emittance Measurements. A data-record-
ing and processing attachment has been built and installed on a double-beam,
ratio-recording spectrometer. The device automatically records corrected
spectral emittance data on punched paper tape. Data from the tape can be
entered directly into an electronic digital computer for computation of total
emittance or the integrated absorptance for radiation of known spectral dis-
tribution. The attachment can also be used to compute any of these prop-
erties during a determination of spectral emittance by the selected ordinate
method. This device was developed in a program sponsored by the Air
Force.

Thermal Conductivity Reference Materials. Thermal conductivity
reference samples are needed by industry and other laboratories* to confirm
or compare thermal conductivity measurements, or to calibrate comparative
methods of conductivity measurement. Extensive measurements to explore
the stability of a chromium-nickel alloy, and the degree to which it may be
affected by its thermal history, have been made using electrical resistance
measurements. Thermal conductivity results made by a cooperating labora-
tory over the temperature range 200 to 1100 °C on a sample of this alloy
agree with Bureau results within two percent. Sixteen samples of this alloy
have now been made available to other laboratories, on a preliminary basis.
Preliminary work has begun on a cerammed microcrystalline glass in a
program to develop a much needed reference material of moderate thermal
conductivity. This work was supported in part by the Navy.

Measurement of the spectral emittance of a ceramic oxide specimen at 1400 °K.
Because the ceramic oxides have high melting temperature and good
chemical stability, they are useful in furnace linings, fire barriers, rocket nose
cones, and inboard power supplies in space vehicles. For these applications,
however, the high-temperature thermophysical properties, such as thermal
emissivity, of these materials must be carefully charted. (See p. 190.)

191

Thermal Conductivity Measurements by Radial Heat Flow. In

connection with thermal conductivity measurements on powder insulations
at high temperatures, the Bureau made a mathematical analysis of line heat
source arrangements for a radial heat flow system. The study showed that
that the positions of the axial heater and inner radius thermocouples of a
radial-flow system could be interchanged, with material experimental advan-
tages in some cases. For example, one thermocouple can serve in place of
several, and can be protected against contamination, or be renewed readily,
without disturbing a measurement.

Performance Specification for Insulated Flat-Roof Constructions.
A draft of a performance specification for insulated flat-roof construction
subjected to moisture has been prepared for the Army, Navy, and Air Force,
the sponsors of the investigation. The specification gives performance re-
quirements for insulated roof constructions, for ordinary occupancy and
climates, that are capable, if wetted, of self-drying under seasonal in-service
conditions as a result of solar heating of the roof. The studies showed that
after the leak is patched, an insulated flat roof, if it is self-drying, will re-
cover most of its insulating value, without replacing the insulation or the
roofing.

Heat of Hydration of Portland Cement. As portland cement hy-
drates, a substantial amount of heat is released. To prevent damage to
massive structures, such as large dams, by the accumulation and subsequent
release of the heat generated within the structure, designers must know the
heat of hydration of various cements. Calorimeters for determining these
data are calibrated with reagent-quality zinc oxide. Heat-of-solution values
currently used for zinc oxide were determined in 1933.

One of three sets of equipment used to check cement and concrete testing,
apparatus by the NBS Cement and Concrete Reference Laboratory in a joint
U.S. Government — ASTM program. The service is available throughout the
United States and Canada.

192

Recently, using a precision calorimeter, the Bureau determined the heat
of solution of 12 lots of reagent-quality zinc oxide obtained from different
manufacturers in the United States, Great Britain, Germany, and Japan.
Results showed an average value only slightly higher than the currently
accepted value. Further, no significant differences in heat of solution were
found among the 12 lots. Consequently, measurements made with different
cement calorimeters, wherever calibrated, should not differ from each other
due to differences in the source of the standardizing substance.

Electron Capture of Combustion Inhibitors, Certain gaseous flame-
inhibiting agents show high electron attachment coefficients. Results of
electron attachment studies on 23 halogenated hydrocarbons show that they
exhibit electron attachment coefficients significantly higher than that of
oxygen. There appeared, with some exceptions, to be qualitative correlation
between electron attachment and flame extinguishment effectiveness of the
inhibitors. However, the significance of this finding is not clear, considering
that there are compounds exhibiting high electron attachment coefficients
which cannot be considered useful as flame inhibitors.

Surface Flame Propagation. The radiant-panel flame-spread test
method, previously developed by the Bureau, has been adopted as an Interim
Federal Standard and as a tentative test method for research and develop-
ment purposes by the ASTM. Performance of this test results in a flame-
spread index composed of two factors, representing the ignition sensitivity
and the maximum rate of heat generation by the material. Recently com-
pleted studies on selected cellulose-type materials have delineated some
important physical and thermal properties which influence surface flame
propagation on simple and composite slabs. Results of these studies indicate
that flame propagation in these materials consists of progressive ignition of
the solid when a characteristic temperature is reached.

Fire Research Contracts. The Bureau, in cooperation with the Office
of Naval Research, the Office of Civil Defense, the Advanced Research Proj-
ects Agency, and the National Science Foundation, is supporting funda-
mental work in the field of self-ignition phenomena and the mechanism of
fire extinguishment. Two aspects of this work have been completed by pub-
lication of the findings. The first of these consisted of a study of combustion
phenomena by means of mathematical techniques. The refinements intro-
duced in this study for predicting performance of self-heating materials,
show that the finite difference method developed provides a significant im-
provement over other mathematical techniques previously available.

In the second part of the study, the field of fire extinguishment, research
for the purpose of clarifying the mechanism by which chemical powders are
effective in terminating combustion reactions, has been studied. It was
found that the introduction of 6 percent potassium vapor into a methane
diffusion flame had no inhibition effect, but bromine compounds introduced
at the same concentration proved to be very effective inhibitors.

193

2.3.7. WEIGHTS AND MEASURES

The control over commercial weighing and measuring in the United States
is principally the responsibility of the political subdivisions of the Federal
government — the States, counties, and cities. Such local control allows
problem solutions to be patterned to local conditions. However, to avoid
the possibility of 50 different weights and measures systems, the U.S. Depart-
ment of Commerce — and through it, the National Bureau of Standards —
has been charged by the Congress with the custody, maintenance, and de-
velopment of the national standards of measurement, and with the provision
of means and methods for making measurements consistent with those stand-
ards. To assist the State weights and measures programs, the Bureau tests
and calibrates State standards and standard measuring apparatus and pro-
vides technical advisory services. To assure uniformity in weights and
measures laws and in methods of inspection, the Bureau extends general
cooperation to State weights and measures officials.

To carry out this program, the Bureau maintains an Office of Weights
and Measures which is responsible for ( 1 ) technical assistance to the States
and to business and industry in the area of measurement; (2) the design,
construction, and use of weights and measures standards and of instruments
associated with such standards; (3) the training of weights and measures
officials in the technical aspects of their programs; and (4) the collection,
arrangement, and dissemination of technical data on measurement units
and systems.

Technical Assistance Program. With increases in personnel, the Of-
fice of Weights and Measures has expanded its technical services, and as-
sistance is now being given on a continuing basis in the design of State
laboratory facilities. During the year, plans for such facilities have been
provided to the States of New Mexico, Pennsylvania, Tennessee, and
Wisconsin.

Package-checking techniques for products that are difficult to check — for
example, aerosol containers and frozen food packages — were outlined and
demonstrated. For such products, dependable quantity determination meth-
ods have not previously been available in convenient form for weights and
measures officials.

A preliminary investigation was made of pipe meter provers, with more
detailed studies planned. In an investigation undertaken because of the
recent use of small flowmeters in the marketing of fuel oil, a system was
developed for the testing of so-called "slow-flow" meters. An extensive
investigation of the accuracy of rental-car odometers was completed.

A new form of communication with the weights and measures officials of
the Nation, the Weights and Measures Tech Memo, was initiated. This memo
is issued at practical intervals to selected addresses, principally to State
offices. Thus information on significant technical developments is trans-
mitted to the operating level.

194

A booklet containing simplified test procedures has been prepared for use
in the testing of commerical weighing and measuring devices. These pro-
cedural outlines list the minimum steps to be followed in an official
examination.

New Standards Designed. New mass standards made of stainless steel
were recently designed. Orders for a set of metric weights of this design
have been placed with manufacturers, as part of a Latin-American Standards
development program.

In studies to improve State and industrial equipment, glass capacity
measures were developed which are both easy to use and nearly automatic
in operation and, at the same time, give highly accurate results; and a 100-
gallon stainless steel capacity measure was designed for use as a capacity
standard and also for use in the calibration of sanitary meters.

Technical Training. Technical training of State and local weights and
measures officials falls into three categories: formal courses of one-week
duration for small classes of supervisory personnel in a training laboratory
at the Bureau; 2-, 3-, or 4-day formal courses conducted in the various States
for all State and local officials; and informal training at the Bureau and in
the field to cover laboratory procedures and the use of special testing equip-
ment. Such technical training undoubtedly is a factor in the rapidly devel-
oping uniformity and effectiveness of weights and measures regulatory
services in the United States. This year, in line with the desire to reach
the greatest number of weights and measures officials possible, self-training
aids were created as a supplement to the formal training programs.

Standard glass capac-
ity measures recently
designed at the Bu-
reau for weights and
measures officials are
easy to use, nearly au-
tomatic in operation,
and highly accurate.
(See p. 195.)

195

New design for mass standards made of stainless steel. A metric set of this
design is being acquired for the Latin American standards program. (See
p. 195.)

Technical Information. A basic responsibility is the dissemination
of accurate information on units, systems, and equivalents of weights and
measures. Tables of interrelation in forms that facilitate ready reference are
published, and a large volume of inquiries for technical information is
handled every year. Two indexed collections of books — an archival collec-
tion and a reference collection — and many historical documents comprise a
weights and measures library. This library affords the staff and outside
researchers and students complete references on the history and present
status of weights and measures.

National Conference on Weights and Measures. The Bureau spon-
sors an annual National Conference on Weights and Measures where
weights and measures officials, representatives of various agencies of the
Federal government and of equipment manufacturers and users, and others
interested in orderly and effective weights and measures control are as-
sembled for relatively informal meetings. The Conference sessions develop
technical and general recommendations for weights and measures adminis-
tration, contribute to interstate coordination of weights and measures activ-

196

ity, and explore the entire area of this economically important segment of
governmental regulatory service. Among Conference accomplishments are
a Model State Law on Weights and Measures, and model regulations covering
devices and packages. The Model Law is included among recommended
legislative efforts of the Council of State Governments.

At the 48th National Conference held during the year, 39 States, the Dis-
trict of Columbia, Canada, Puerto Rico, England, Austria, and Trinidad
and Tobago were officially represented among a total attendance of 499.
Principal topics discussed were package standardization and labeling, slow-
flow meter tolerances, and rental-car odometer accuracy. Talks were pre-
sented on such subjects as the President's Consumer Advisory Council, the
International Organization of Legal Metrology, domestic and international
business, consumer protection in Great Britain, the Truth in Packaging Bill,
and problems in the determination of moisture and quantity control.

3. APPENDIXES

3.1. ORGANIZATION OF THE NATIONAL BUREAU

OF STANDARDS*

The Bureau is headed by a Director who is appointed by the President with Senate
confirmation. The Director is assisted by two Deputy Directors, one who is responsible
for basic standards and services, and the other for technological standards and services.
The Associate Directors participate in the leadership function, coordinating related
technical work across division lines, heading important policy committees, and handling
special assignments in a staff capacity. One of the Associate Directors, in addition to
being responsible for administration and support activities of a continuing nature, is
in charge of the relocation of the Bureau to new laboratories which are under constuc-
tion at Gaithersburg, Maryland. Program activities are conducted in 24 scientific divi-
sions. Most divisions correspond roughly to a major field of physical science or
engineering, and are divided into sections responsible for technical areas within each
field. Sixteen of the divisions are located in Washington and eight in Boulder. Below
the section level, the staff is organized into project groups which may be easily regrouped.

DIRECTOR

Allen V. Astin

DEPUTY DIRECTORS
Robert D. Huntoon

I. C. SCHOONOVER

Associate Directors

L. S. Taylor
R. S. Walleigh

W. A. WlLDHACK

Manager, Boulder Laboratories

R. B. Scott

*As of June 30, 19GS.

197

Assistants to the Director

G. E. Auman

W. S. Bussey

W. H. Gammon

A. T. McPherson

Assistant Directors and Senior Research Fellows

U. Fano
K. Shuler

Senior Research Fellows

C. ElSENHART

J. R. Wait
Staff Advisers

Patent Adviser
Program Adviser

D. Robbins

C. N. COATES

NBS WASHINGTON
SCIENTIFIC DIVISIONS AND SECTIONS

(In numerical order)

ELECTRICITY

Chief

Resistance and Reactance

Electrochemistry

Electrical Instruments

Magnetic Measurements

Dielectrics

High Voltage

Absolute Electrical Measurements

C. H. Page

C. Peterson

W. J. Hamer

M. Defandorf

I. L. Cooter

J. D. Hoffman

F. R. Kotter

F. K. Harris

METROLOGY

Chief
Assistant Chief

Photometry and Colorimetry

Refractometry

Photographic Research

Length

Engineering Metrology

Mass and Volume

A. G. McNish
D. B. Judd
L. E. Barbrow
F. E. Washer
C. S. McCamy
T. R. Young
I. H. Fullmer
P. E. Pontius

HEAT

Chief

Assistant Chief for Thermodynamics

Temperature Physics

Heat Measurements

Cryogenic Physics

Equation of State

Statistical Physics

RADIATION PHYSICS

Chief

X-ray

Radioactivity

Radiation Theory

High Energy Radiation

Radiological Equipment

Nucleonic Instrumentation

Neutron Physics

R. P. Hudson

C. W. Beckett

J. F. Swindells

D. C. Ginnings

E. Ambler

J. Hilsenrath

M. S. Green

H. W. Koch
H. 0. Wyckoff
W. B. Mann

M. Berger. Acting

J. E. Liess, Acting

S. W. Smith

L. Costrell

R. S. Caswell

198

ANALYTICAL AND INORGANIC CHEMISTRY

Chief

Assistant Chief
Consultant

Pure Substances

Spectrochemistry

Solution Chemistry

Standard Reference Materials

Applied Analytical Research

Crystal Chemistry

MECHANICS

Chief
Consultants

Sound

Pressure and Vacuum

Fluid Mechanics

Engineering Mechanics

Rheology

Combustion Controls

POLYMERS

Chief

Consultants on Leather

Paper

Plastics

Rubber

Textiles
Macromolecules : Synthesis and Structure
Polymer Chemistry
Polymer Physics
Polymer Characterization
Polymer Evaluation and Testing
Applied Polymer Standards and Research
Dental Research

METALLURGY

Chief

Assistant Chief
Consultant
Special Assistant

Engineering Metallurgy

Metal Reactions

Metal Physics

Electrolysis and Metal Deposition

INORGANIC SOLIDS
Chief

Assistant Chief
Consultant
Vitreous State Group

Engineering Ceramics

Glass

Solid State Chemistry

Crystal Growth

Physical Properties

Crystallography

BUILDING RESEARCH

Chief
Consultant

Structural Engineering

Fire Research

Mechanical Systems

Organic Building Materials

Codes and Safety Standards

Heat Transfer

Inorganic Building Materials

Metallic Building Materials

H. C. Allen
R. G. Bates
C. P. Saylor
F. L. Howard
B. F. Scribner
R. G. Bates
J. L. Hague
J. K. Taylor
H. S. Peiser

B. L. Wilson
J. M. Frankland
E. C. Lloyd
R. K. Cook
D. P. Johnson
G. B. Schubauer
L. K. Irwin
R. S. Marvin
F. R. Caldwell

G. M. Kline

J. R. Kanagy

R. B. Hobbs

S. G. Weissberg

L. A. Wood

H. F. SCHIEFER

D. McIntyre
L. A. Wall

E. Passaglia
N. P. Bekkedahl

R. D. Stiehler

R. B. Hobbs

W. T. Sweeney

L. M. Kushner
G. A. Ellinger
L. L. Wyman
H. C. Burnett
S. J. Rosenberg
G. A. Ellinger
L. M. Kushner
A. Brenner

A. D. Franklin
C. H. Hahner
E. R. Lippincott
A. B. Bestul
M. B. Burdick
C. H. Hahner
Vacant
F. Ordway
J. B. Wachtman, Jr.
H. F. McMurdie

A. A. Bates

W. F. Roeser

D. Watstein

A. F. Robertson

P. R. Achenbach

W. W. Walton

Vacant

H. E. Robinson

B. E. Foster

W. N. Harrison

714-691 0—64-

199

APPLIED MATHEMATICS

Chief

Assistant Chief
Consultants

Numerical Analysis
Computation
Statistical Engineering
Mathematical Physics
Operations Research

DATA PROCESSING SYSTEMS

Chief

Technical Assistant
PILOT

Research Information Center and Advisory
Service on Information Processing

Components and Techniques

Computer Technology

Measurements Automation

Engineering Applications

Systems Analysis

E. W. Cannon

F. L. Alt

W. J. Youden

Mrs. Ida Rhodes

M. Newman

D. I. MlTTLEMAN

J. M. Cameron

W. H. Pell

A. J. Goldman

S. N. Alexander
M. R. Fox
J. P. Nigro

Chief

Spectroscopy
Infrared Spectroscopy
Far Ultraviolet Physics
Solid State Physics
Electron Physics
Atomic Physics
Plasma Spectroscopy

Chief

Engineering Electronics
Electron Devices
Electronic Instrumentation
Mechanical Instruments
Basic Instrumentation

ATOMIC PHYSICS

INSTRUMENTATION

Miss M. E. Stevens

R. D. Elbourn

J. A. Cunningham

R. T. Moore

J. P. Nigro

S. N. Alexander, Acting

K. G. Kessler

W. C. Martin, Jr.

E. K. Plyler

R. P. Madden

H. P. R. Frederikse

J. A. Simpson

H. Boyne

W. L. Wiese

G. F. Montgomery

G. Shapiro

C. P. Marsden

F. Montgomery, Acting

A. Wexler

J. Stern

PHYSICAL CHEMISTRY

Chief
Consultants

Thermochemistry

Surface Chemistry

Organic Chemistry

Molecular Spectroscopy

Elementary Processes

Mass Spectrometry

Photochemistry and Radiation Chemistry

M. B. Wallenstein
W. L. Clinton
E. J. Prosen
M. B. Wallenstein
R. Klein
H. S. Isbell
D. E. Mann
R. E. Ferguson
H. Rosenstock
J. R. McNesby

Chief

OFFICE OF WEIGHTS AND MEASURES

ADMINISTRATIVE AND SERVICE DIVISIONS

M. W. Jensen

Office of Technical Information

Accounting

Personnel

Administrative Services

Shops

Supply

Management Planning

Budget

Internal Audit

Plant

NBS Library

W. R. Tilley

J. Seidenberg

G. R. Porter

H. P. Dalzell

F. P. Brown

G. B. Kefover

A. J. Miller

J. E. Skillington

J. Seidenberg. Acting

M. B. Goetz. Acting

Miss S. Jones

200

BOULDER DIVISIONS

Manager, Boulder Laboratories

Consultants

Mathematics Group and Computation Facility

Mathematical Physics and Educational Director

Statistics

Physics of the Atmosphere

Communications Liaison Officer

Executive Officer and Chief of Administrative Division

Technical Information Officer

R. B. Scott

J. J. Sopka

E. H. Brown

E. L. Crow

D. M. Gates

Allen Barnabei

S. W. J. Welch

J. R. Craddock

CRYOGENIC ENGINEERING LABORATORY

Chief

Cryogenic Processes
Cryogenic Properties of Solids
Properties of Cryogenic Fluids
Cryogenic Technical Services

B. W. Birmingham, Acting

B. W. Birmingham

R. H. Kropschot

R. J. Corruccini

V. J. Johnson

CENTRAL RADIO PROPAGATION LABORATORY

Chief

Assistant Chief

Chief, Office of CRPL Liaison and Program Development

Consultant, Radio Wave Propagation

IONOSPHERE RESEARCH AND PROPAGATION

C. G. Little

J. W. Herbstreit

A. H. Shapley

J. R. Wait

Chief

Assistant Chief

Assistant to Chief for Technical Planning and Coordination

Consultants

Ultra Low Frequency Research

Low Frequency and Very Low Frequency Research

Ionosphere Research

Prediction Services

Sun-Earth Relationships

Field Engineering

Radio Warning Services

Vertical Soundings Research

R. W. Knecht
T. N. Gautier
J. A. Kemper
D. K. Bailey
H. H. Howe
W. H. Campbell
A. G. Jean
K. Davies
Mrs. M. Leftin
T. E. Van Zandt
H. G. Sellery
Miss J. V. Lincoln
J. W. Wright

TROPOSPHERE AND SPACE TELECOMMUNICATIONS

Chief

Assistant Chief for Research and Development
Consultant — Terminal Equipment
Consultant — Lower Atmospheric Physics

Data Reduction Instrumentation

Radio Noise

Tropospheric Measurements

Tropospheric Analysis

Spectrum Utilization Research

Radio Meteorology

Lower Atmosphere Physics

RADIO SYSTEMS

Chief

Assistant Chief
Assistant Chief

Applied Electromagnetic Theory

High Frequency and Very High Frequency Research

Frequency Utilization

Modulation Research

Antenna Research

Radiodetermination

K. A. Norton
R. S. Kirby
E. F. Florman
B. R. Bean
W. E. Johnson
W. Q. Crichlow
M. T. Decker
P. L. Rice
A. P. Barsis
R. E. McGavin
R. E. McGavin, Acting

R. C. Kirby

D. W. Patterson

W. F. Utlaut

J. R. JOHLER

L. H. Tveten

G. W. Haydon

C. C. Watterson

H. V. Cottony

G. Hefley

201

UPPER ATMOSPHERE AND SPACE PHYSICS

Chief

Assistant Chief
Consultants

Upper Atmosphere and Plasma Physics
High Latitude Ionospheric Physics
Ionosphere and Exosphere Scatter
Airglow and Aurora
Ionospheric Radio Astronomy

RADIO STANDARDS LABORATORY

Chief

Assistant Chief for Planning and Coordination

Consultant

RADIO STANDARDS PHYSICS
Chief

Assistant Chief
Consultant
Assistant Chief for Technical Planning and Coordination

Frequency and Time Dissemination

Radio and Microwave Materials

Atomic Frequency and Time Interval Standards

Radio Plasma

Microwave Physics R. W.

RADIO STANDARDS ENGINEERING

Chief

Assistant Chief

Assistant to the Chief for Technical Planning and Coordination

Consultants

E. K. Smith, Jr.
F. L. Taylor
R. J. Slutz
D. K. Bailey
R. M. Gallet
J. A. Chivers
K. L. Bowles
F. E. Roach

R. S. Lawrence

J. M. Richardson

E. C. Wolzien

D. M. Kerns

Yardley Beers
G. E. Hudson
P. F. Wacker
W. D. Goring
A. H. Morgan
J. L. Dalke
R. C. Mockler
K. B. Persson
Zim merer, Acting

Coordinator Calibration Service
High Frequency Electrical Standards
High Frequency Calibration Services
High Frequency Impedance Standards
Microwave Calibration Services
Microwave Circuit Standards
Low Frequency Calibration Services

G. E. SCHAFER

H. W. Lance
W. J. Anson
R. W. Beatty
M. C. Selby
W. F. Snyder
C. M. Allred
R. C. Powell, Acting
R. C. Powell
R. E. Larson
M. B. Hall
F. D. Weaver, Acting

JOINT INSTITUTE FOR LABORATORY ASTROPHYSICS

Chairman

NBS GROUP
FIELD ESTABLISHMENTS

Visual Landing Aids Field Laboratory
Master Railway Track Scale Depot
Materials Testing Laboratories:

Radio Transmitting Station WWV

Radio Transmitting Station WWVL

Radio Transmitting Station WWVL-WWVB

Central Radio Propagation Laboratory Field Stations:

ALASKA

Anchorage

Barrow

AUSTRALIA

Cook**

BOLIVIA
La Paz**

ANTARCTICA
Byrd Station**
Eights Station**
Pole Station**
USNS Eltanin (Floating CALIFORNIA
Research Vessel)** Port Arguello

BRAZIL, S.A.

Sao Jose dos Campos**

L. M. Branscomb

Areata, Calif.

Clearing, 111.

Denver, Colo.

San Francisco, Calif.

Seattle, Wash.

Greenbelt, Md.

Sunset, Colo.

Fort Collins, Colo.

CANADA
Baie St. Paul
Cape Jones**
Great Whale River**
Frobisher Bay**

CHILE

Concepcion**

♦♦Contract or Mutual Cooperation.

202

COLORADO

Beulah

Brighton

Chalk Cliff Site

Cheyenne Mountain

Erie

Fritz Peak

Green Mountain Mason

Gunbarrel Hill

Haswell

Hygiene

Karval

Kendrick

Kolb

Lafayette

Table Mesa

Sunset

COLOMBIA

Bogota**

GREENLAND
Thule**
Godhavn**
Narssarssuaq**

HAWAII

Maui (WWVH)

Kekaha

Mt. Haleakala

ICELAND
Keflavik**
Reykjavik**

ILLINOIS

Long Branch

INDIA

New Delhi**

JAPAN
Ohira**

KANSAS
Garden City

MALAYA

Singapore**

MISSOURI
Warrensburg

MOROCCO

Rabat**

NEBRASKA

Shickley

NIGERIA

Ibadan**

OKINAWA

Onna**
Okuma**

OKLAHOMA
Altus

PANAMA CANAL ZONE
Balboa**

PERU

Lima**

Jicamarca Radio
Observatory

PHILIPPINE ISLANDS
Baguio

SOUTH AFRICA
Pretoria**

SWEDEN

Enkoping**

UTAH

Salt Lake City**

VIRGINA

Fort Belvoir
Front Royal
Wallops Island

WYOMING

Bill

♦♦Contract or Mutual Cooperation.

3.2. SUMMARY OF NBS STAFF

Washington

Boulder

Total

Total permanent staff

Other staff*

2,350
404

1,168
238

3,518
642

Total on rolls

Research associates and guest workers

2,754
163

1,406
34

4,160
197

Total on rolls at NBS**

2,917

1,440

4,357

Professional staff***

Physicists

423

280

166

221
7

161
59
19

644

Chemists

287

Engineers

Mathematicians

Other

327

109

Total professional staff

995

467

1,462

*WAE, consultants, students, teachers, postdoctoral fellows, and temporary-limited employees.

**Asof June 30, 1963.

***Full-time permanent (excludes any under *) as of December 31, 1962.

203

3.3. FINANCIAL DATA ON NBS PROGRAM

The activities of the National Bureau of Standards are financed from
three sources: from appropriations provided by the Congress; from pay-
ments by other agencies for specific research and development tasks;
and from payments by industrial concerns, universities, research institu-
tions, and government agencies for specific calibration or testing services.
The following tabulation is a summary of the financial aspects of the
Bureau programs for 1963:

Program and source of financing

Obligations incurred (rounded)

Supported by NBS appropriations:
Operating programs:

Research and technical services. .
Special foreign currency program .

$27, 782, 000
710, 000

$28, 492, 000
9, 627, 000

$38, 119.
20, 902,

Subtotal

7, 204, 000
2, 423, 000

Construction and facilities program:

Plant and facilities

Construction of facilities

Subtotal

14, 416, 000
168, 000

Total NBS appropriation

Supported by other funds:

Research and development programs:

Other Federal agencies

Nongovernmental sources

14, 584, 000

5, 462, 000
856, 000

000

Calibrations, testing, standard
samples, and other technical

Reimbursable administrative serv-
ices

Total supported by other funds. .

000

Total program

59, 021,

000

3.4. ADVISORY COMMITTEES

STATUTORY VISITING COMMITTEE

(Reports annually to Secretary of Commerce on NBS activities (. Dates indicate expira-
tion of appointment) )
Dr. Lloyd V. Berkner, President, Graduate Research Center, Inc. (1963), Chairman
Professor Frederick Seitz, President, National Academy of Sciences (1966)
Mr. Crawford H. Greenwalt, President, E. I. du Pont de Nemours & Co. (1964)
Professor Charles H. Townes, Provost, Massachusetts Institute of Technology (1965)
Dr. E. R. Piore, Vice President, Research and Engineering, International Business
Machines Corporation (1967)

204

TECHNICAL ADVISORY PANELS

At the request of the National Bureau of Standards, the National Academy of Sciences-
National Research Council, in cooperation with the leading scientific and technical
societies, appoints each year a number of technical advisory panels. The panels make
a continuing evaluation of NBS programs with respect to the needs of the Nation's
scientific and technological community. The panels provide advice and information in
specific technical areas for use by the NBS Director and his staff in the formulation
and execution of NBS programs.

Cooperating societies are: American Ceramic Society (ACerS) ; American Chemical
Society (ACS) ; American Institute of Chemical Engineers (AIChE) ; Institute of Elec-
trical and Electronic Engineers (IEEE) ; American Institute of Mining, Metallurgical,
and Petroleum Engineers (AIME) ; American Institute of Physics (AIP) ; American
Society of Civil Engineers (ASCE) ; American Society of Mechanical Engineers
(ASME) ; and Conference Board of the Mathematical Sciences (CBMS) .

Dr. Paul D. Foote, National Research Council, Executive Secretary

Advisory Panel to Electricity Division

Prof. W. A. Lewis, Illinois Institute of Technology, Chairman (IEEE)

Dr. William G. Amey, Leeds & Northrup (IEEE)

Dr. Richard M. Bozorth, Short Hills, N.J. (AIP)

Dr. John Brainerd, University of Pennsylvania (IEEE)

Prof. Henry B. Linford, Columbia University (ACS)

Mr. J. T. Lusignan, The Ohio Brass Company (IEEE)

Prof. John G. Trump, Massachusetts Institute of Technology (AIP)

Dr. Ernest Weber, Polytechnic Institute of Brooklyn (IEEE)

Advisory Panel to Metrology Division

Dr. Brian O'Brien, Pomfret, Conn., Chairman (AIP)
Prof. Isay A. Balinkin, University of Cincinnati (ACerS)
Dr. Alsoph H. Corwin, The Johns Hopkins University (ACS)
Mr. C. L. Crouch, Illuminating Engineering Society (AL)
Mr. A. M. Dexter, Pratt and Whitney Company, Inc. ( AL)
Dr. Robert E. Hopkins, University of Rochester (AL)
Mr. Floyd W. Hough, Arlington, Virginia (ASCE)
Dr. Elmer Hutchisson, American Institute of Physics (AIP)
Mr. J. J. Moran, Kimble Glass Company (ACerS)
Mr. Louis Polk, Dayton, Ohio (ASME)
Prof. John Strong, The Johns Hopkins University (AIP)
Dr. J. H. Webb, Eastman Kodak Company (AIP)

Advisory Panel to Heat Division

Prof. Joseph E. Mayer, University of California, Chairman (ACS)

Prof. James A. Beattie, Massachusetts Institute of Technology (AIP)

Prof. Henry A. Fairbank, Duke University (AIP)

Dr. Burgess H. Jennings, Northwestern University (ASME)

Prof. Joseph Kestin, Brown University (ASME)

Dean R. B. Lindsay, Brown University (AIP)

Dr. Charles Squire, Agriculture and Mechanical College of Texas (AIP)

Prof. Glenn C. Williams, Massachusetts Institute of Technology (AICE)

Advisory Panel to Radiation Physics Division

Dr. H. M. Parker, General Electric Company, Chairman (AIP)

Mr. Everitt P. Blizard, Oak Ridge National Laboratory (AIP)

Dr. Martin Deutsch, Massachusetts Institute of Technology (AIP)

Dr. A. O. Hanson, University of Illinois (AIP)

Dr. William A. Higinbotham, Brookhaven National Laboratory (IEEE)

Prof. Harold A. Lamonds, North Carolina State College (IEEE)

Prof. George T. Reynolds, Palmer Physical Laboratory (AIP)

Dr. Leonard Schiff, Stanford University (AIP)

205

Advisory Panel to Analytical and Inorganic Chemistry Division

Dr. T. Ivan Taylor, Columbia University, Chairman (ACS)

Dr. Clark E. Bricker, The College of Wooster (ACS)

Dr. Norman D. Coggeshall, Gulf Research and Development Company (AIP)

Dr. W. D. Cooke, Cornell University (ACS)

Dr. Herbert A. Laitinen, University of Illinois (ACS)

Dr. W. Wayne Meinke, University of Michigan (ACS)

Prof. Henry Taube, Stanford University (ACS)

Dr. Charles E. White, University of Maryland (ACS)

Advisory Panel to Mechanics Division

Prof. S. R. Beitler, Ohio State University, Chairman (ASME)

Prof. Lynn S. Beedle, Lehigh University (ASCE)

Prof. Arthur T. Ippen, Massachusetts Institute of Technology (ASCE)

Dr. Harry F. Olson, Radio Corporation of America (AIP)

Prof. Jesse Ormondroyd, University of Michigan (ASME)

Dr. Milton Plesset, California Institute of Technology (AIP)

Advisory Panel to Polymers Division

Dr. C. G. Overberger, Polytechnic Institute of Brooklyn, Chairman (ACS)

Dr. Raymond F. Boyer, Dow Chemical Company (ACS)

Dr. J. H. Dillon, Textile Research Institute (AIP)

Dr. Milton Harris, Harris Research Laboratories, Inc., (ACS)

Dr. Frank C. McGrew, E. I. du Pont de Nemours & Co. (ACS)

Dr. Charles C. Price, University of Pennsylvania (ACS)

Dr. J. F. Downie Smith, Carrier Research and Development Company (ASME)

Dr. Charles Scott Venable, Wallingford, Pa. (ACS)

Advisory Panel to Metallurgy Division

Mr. Francis L. Laque, International Nickel Company, Chairman (ACS)

Dr. D. J. Dienes, Brookhaven National Laboratory (AIP)

Dr. Morris Eugene Fine, Northwestern University (AIME)

Mr. A. R. Lytle, National Academy of Sciences-National Research Council (AIME)

Dr. Oscar Marzke, United States Steel Corporation (AIME)

Prof. E. F. Osborn, Pennsylvania State University ( ACerS)

Dr. Joseph A. Pask, University of California (ACerS)

Dr, Albert J. Phillips, American Smelting and Refining Company (AIME)

Mr. D. B. Rossheim, M. W. Kellogg Corporation (ASME)

Mr. J. H. Scaff, Bell Telephone Laboratories (AIME)

Prof. Robb M. Thompson, University of Illinois (AIP)

Advisory Panel to Inorganic Solids Division

Dr. Norbert J. Kreidl, Bausch and Lomb Optical Company, Chairman (ACerS)

Dr. Orson L. Anderson, Summit, New Jersey (ACerS)

Prof. C. Ernest Birchnall, University of Delaware ( AL)

Dr. Joseph E. Burke, General Electric Research Laboratory (ACerS)

Dr. James R. Johnson, Minnesota Mining and Manufacturing Company lACerS)

Prof. J. W. Mitchell, University of Virginia (AL)

Dr. E. F. Osborn, Pennsylvania State University (ACerS)

Dr. Ralston Russell, Jr., The Ohio State University (ACerS)

Mr. Karl Schwartzwalder, General Motors Corporation (ACerS)

Prof. Pierce Selwood, University of California (ACS)

Advisory Panel to Building Research Division

Dr. W. C. Hansen, Valpariso, Indiana, Chairman (ACS)

Prof. Jesse H. Day, Ohio University (ACS)

Dr. Albert G. H. Deitz, Massachusetts Institute of Technology (ASCE)

Dr. J. V. Fitzgerald, Tile Council of America, Inc. (ACerS)

Prof. Robert A. Hechtman, The George Washington University (ASCE)

Prof. James T. Lendrum, University of Florida ( AIA)

Dean Warren L. McCabe, Polytechnic Institute of Brooklyn ( AICE)

Dr. John S. Parkinson, Johns-Manville Products Corporation (AIP)

Prof. E. R. Queer, The Pennsylvania State University (AL)

Mr. Raymond C. Reese, Toledo, Ohio (ASCE)

206

Advisory Panel to Applied Mathematics Division

Prof. Georce E. Forsythe, Stanford University, Chairman (CBMS)

Prof. A. H. Bowker, Stanford University (AL)

Prof. Jesse Douglas, City College of New York (AL)

Prof. William Feller, Princeton University (CBMS)

Dr. Alston S. Householder, Oak Ridge National Laboratory (CBMS)

Prof. B. 0. Koopman, Columbia University (CBMS)

Prof. Peter D. Lax, New York University (CBMS)

Dr. Elliott W. Montroll, Institute for Defense Analysis (CBMS)

Prof. R. D. Richtmyer, New York University (CBMS)

Dr. J. Barkley Rosser, Cornell University (CBMS)

Prof. M. M. Schiffer, Stanford University (CBMS)

Advisory Panel to Data Processing Systems Division

Dr. Alston S. Householder, Oak Ridge National Laboratory, Chairman (CBMS)

Prof. George E. Forsythe, Stanford University (CBMS)

Dr. Alan J. Hoffman, International Business Machines Corporation (CBMS)

Mr. John C. McPherson, International Business Machines Corporation (IEEE)

Prof. Charles L. Miller, Massachusetts Institute of Technology (ASCE)

Mr. William Papian, Massachusetts Institute of Technology (IEEE)

Prof. Raymond Pepinsky, Pennsylvania Slate University (AIP)

Prof. William H. Radford, Massachusetts Institute of Technology (IEEE)

Prof. Morris Rubinoff, University of Pennsylvania (IEEE)

Advisory Panel to Atomic Physics Division

Prof. R. H. Dicke, Princeton University, Chairman (AIP)

Prof. Benjamin Bederson, New York University (AIP)

Dr. Bruce H. Billings, Baird-Atomic, Inc. (AIP)

Prof. Peter Franken, University of Michigan (AIP)

Prof. Jesse L. Greenstein, California Institute of Technology ( AL)

Prof. Vernon W. Hughes, Sloane Laboratory (AIP)

Prof. Mark G. Ingrham, University of Chicago (AIP)

Dr. Benjamin Lax, Massachusetts Institute of Technology (AIP)

Dr. M. Kent Wilson, Tufts University (ACS)

Advisory Panel to Instrumentation Division

Mr. R. W. Larson, General Electric Research Laboratories, Chairman

Dr. A. 0. Beckman, Beckman Instruments, Inc. (AL)

Mr. Ivan G. Easton, General Radio Company (IEEE)

Mr. D. G. Fink, Philco Corporation (IEEE)

Mr. William R. Hewlett, Hewlett-Packard Company (IEEE)

Dr. R. J. Jeffries, Data-Control Systems, Inc. (AL)

Col. J. Z. Millar, Western Union Telegraph Company (IEEE)

Mr. Leon Podolsk y, Sprague Electric Company (IEEE)

Advisory Panel to Physical Chemistry Division

Prof. Henry Eyring, University of Utah, Chairman (ACS)

Dr. A. 0. Allen, Brookhaven National Laboratory (ACS)

Dr. Paul Cross, Mellon Institute of Industrial Research (ACS)

Dr. Benjamin P. Dailey, Columbia University (ACS)

Dr. Joseph 0. Hirschfelder, University of Wisconsin (ACS)

Prof. Hans H. Jaffe, University of Cincinnati (ACS)

Dr. Daniel R. Stull, The Dow Chemical Company (ACS)

Advisory Panel to Cryogenic Engineering Division

Dr. Clyde McKinley, Air Products Incorporated, Chairman (AICE)

Prof. A. L. Hesselschwerdt, Massachusetts Institute of Technology (ASME)

Dr. Hugh M. Long, Tonawanda, New York (AIP)

Dr. Loyd B. Nesbitt, General Electric Laboratory (AIP)

Dr. David White, Ohio State University (ACS)

207

Advisory Panel to Central Radio Propagation Laboratory

Prof. Arthur H. Waynick, The Pennsylvania State University, Chairman (IEEE)

Mr. Stuart L. Bailey, Alexandria, Va. (IEEE)

Prof. Henry G. Booker, Cornell University (IEEE)

Dr. R. A. Helliwell, Stanford University (IEEE)

Dr. S. W. Herwald, Westinghouse Electric Corporation (IEEE)

Dr. F. S. Johnson, Graduate Research Center (AIP)

Dr. John M. Kelso, ACF Industries, Inc. (IEEE)

Dr. John B. Smyth, Smyth Research Associates (AIP)

Dean George Town, Iowa State University (IEEE)

Advisory Panel to Radio Standards Laboratory

Prof. Arthur A. Oliner, Polytechnic Institute of Brooklyn, Chairman

Dr. Sidney A. Bowhill, University of Illinois (IEEE)

Prof. Walter Gordy, Duke University (AIP)

Prof. E. L. Hahn, University of California (AIP)

Dr. E. W. Houghton, Bell Telephone Laboratories (IEEE)

Prof. E. C. Jordan, University of Illinois (IEEE)

Dr. R. Kompfner, Bell Telephone Laboratories (IEEE)

Prof. W. A. Lewis, Illinois Institute of Technology (IEEE)

Prof. N. F. Ramsey, Harvard University (AIP)

Dr. John C. Simons, National Research Corporation (IEEE)

ADVISORY COMMITTEE ON ENGINEERING AND RELATED

STANDARDS

(Members are nominated by the American Standards Association (ASA) and the
American Society for Testing and Materials ( ASTM) )

Mr. W. A. Wildhack, National Bureau of Standards, Chairman
Mr. Roger E. Gay, American Standards Association (ASA)
Mr. Richard T. Kropf, Belding Heminway Company (ASTM)
Mr. John W. McNair, American Standards Association (ASA)
Mr. N. L. Mochel, Westinghouse Electric Corporation (ASTM)
Mr. Frank H. Roby, American Standards Association (ASA)
Mr. Alfred C. Webber, E. I. du Pont de Nemours, Inc. (ASTM)

ADVISORY COMMITTEE ON CALIBRATION AND MEASUREMENT

SERVICES

(Members are appointed on the basis of their broad personal knowledge of industrial

measurement problems)

Mr. W. A. Wildhack, National Bureau of Standards, Chairman

Mr. Joseph M. Aldrich, San Diego, California

Dr. William G. Amey, Leeds & Northrup Company

Mr. Ivan G. Easton, General Radio Company

Mr. Charles E. Johnson, The Boeing Company

Mr. Sheldon C. Richardson, General Electric Company

Dr. George Sonneman, American Optical Company

Mr. Bruno Weinschel, Weinschel Engineering

Mr. Charles E. White, Avco Research & Advanced Development Division

Mr. L. B. Wilson, Sperry Gyroscope Company

WEIGHTS AND MEASURES ADVISORY COMMITTEE

(Members are nominated by the National Conference on Weights and Measures)

Mr. W. S. Bussey, National Bureau of Standards, Chairman

Miss Genevieve Blatt, Secretary of Internal Affairs, Commonwealth of Pennsylvania

Mr. John Hoyt Chaloud, Ivorydale Technical Center

Mr. C. G. Gehringer, Howe-Richardson Corporation

Prof. L. J. Gordon, Weights and Measures Research Center, Denison University

Mr. Rollin E. Meek, State Board of Health, Indiana

Mr. Donald Malcolm Turnbull, City of Seattle, Comptrollers Department

208

3.5. AWARDS AND HONORS

Recognition of the Bureau's contributions to science and technology often takes the
form of awards and honors from government, academic, professional, and industrial
groups. The following list reflects such recognition bestowed on Bureau staff members
during fiscal year 1963.

RECIPIENT

Bass, Arnold M.
Bowles, Kenneth L.
Carrington, Tucker
Carter, Thomas J.
Craic, Norman
Davis, Philip J.
Hammond, Harry K., Ill
Jackson, Julius L.
Jacox, Marilyn E.
Mandel, John

McIntyre, Donald

McPherson, Archibald T.

Meggers, William
Newman, Sanford B.
Paffenbarger, George C.
Parsons, Douclas E.

Penner, Samuel
Rosenberg, Samuel J.
Schiefer, Herbert F.
Scribner, Bourdon F.

Sweeney, William T.
Taylor, Lauriston S.
Wexler, Arnold
Yakowitz, Harvey

Joint Awards :
Ambler, Ernest
Hayward, Raymond W.
Hoppes, Dale D.
Hudson, Ralph P.
(Wu, Chien Shiung, Columbia

University)
Myerson, Melvin R.
Ney, Wilbert R.
Young, Theodore R.

AWARD

Elected Fellow of Optical Society of America

RESA Boulder Scientist Award

Silver Medal of the Combustion Institute

Benedict College Award for Outstanding Achievement

William Blum Award of the Electrochemical Society

Chaavenet Prize of the Mathematical Association of America

Award of Merit by American Society for Testing and Materials

Fulbright Scholarship

Utica College Award for Outstanding Achievement

Elected Fellow of the American Association for the Advancement
of Science

National Capital Award by D.C. Council of Engineering and Architec-
tural Societies

Outstanding Service Award From the Standards Engineers Society and
the American Society for Testing and Materials

Achievement Award of the Spectroscopy Society of Pittsburgh

Elected Fellow of the Royal Microscopical Society

Achievement Medal from Alpha Omega Fraternity

Walter C. Voss "Award of the American Society for Testing and
Materials

Fellowship from the John Simon Guggenheim Memorial Foundation

Burgess Memorial Award from American Society for Metals

Honorary Doctor of Science Degree from Ferris Institute

Elected Honorary Member of Groupement pour l'Advancement Methodes
Spectrographiques

Annual Award of American Academy for Plastics Research in Dentistry

Orator of the Year of Radiological Society of North America

Elected Fellow of the Instrument Society of America

Award for Prize Photograph submitted to World Metals Congress of
American Society for Metals

John Price Wetherill Medal from Franklin Institute

Charles B. Dudley Medal from American Society for Testing and
Materials

RECIPIENT

Wait, James R.
Joint Award:

Bender, Peter L.

Driscoll, Raymond L.

HIGHEST NATIONAL BUREAU OF STANDARDS AWARD

AWARD

Samuel Wesley Stratton Award
Samuel Wesley Stratton Award

DEPARTMENT OF COMMERCE EXCEPTIONAL SERVICE AWARDS

RECIPIENT

Brenner, Abner
Cameron, Joseph
Frederikse, Hans P. R.
Thomas, Richard N.

TECHNICAL AREA

Electroplating

Modern statistical and computational methods

Solid state physics

Atmospheres of stars

209

DEPARTMENT OF COMMERCE MERITORIOUS SERVICE AWARDS

RECIPIENT

Bean, Bradford R.
Beatty, Robert W.
Block, Stanley
Bussey, Howard E.

Corliss, Charles H.

HlLSENRATH, JOSEPH

Loving, Vernon W.
Mears, Thomas W.
Pincock, Glen
Radford, Harrison E.
Richmond, Joseph C.
Spinner, Sam
Stiehler, Robert D.
Swanson, Howard E.
Woolley, Harold W.
Joint Award:
Pruitt, John S.

Domen, Steve R.

th the interaction of elec-

TECHNICAL AREA

Radio wave refraction
Microwave circuit standards
Analysis of crystal structures
Electromagnetic parameters associated

tromagnetic waves
Quantitative spectroscopy and astrophysics
Conception and development of OMNITAB
Instrument craftsmanship
Standard reference materials
Health of NBS staff

Molecular energy levels and chemical kinetics
Thermal radiation measurements
Dynamic elastic properties

Standardization of rubber and rubber products
Standard x-ray diffraction powder patterns
Thermodynamic properties of gases

Standards for determination of total energy content of high energy
x-ray beams

3.6. EDUCATION AND TRAINING PROGRAM

Available to all staff members at the Bureau is a broad employee develop-
ment program which is implemented primarily through both the NBS Grad-
uate School and nongovernment educational and training facilities. The
program covers educational levels through postdoctoral research. The pro-
gram is offered at both the Boulder and Washington Laboratories; its
primary objectives are the increase of efficiency in the conduct of official
assigned duties and the systematic preparation for increased responsibilities.

The Graduate School curriculum includes graduate and undergraduate
courses in the physical sciences, mathematics, and certain branches of
engineering. Also, a series of scientific colloquia and seminars are led by
research leaders from the Bureau staff and from other research centers. In
addition, general staff development courses, such as scientific German, prac-
tical metallurgy, and mathematical symbolism and terminology, are also
offered. Educational counseling is available and employees may receive
thesis accreditation for research done at the Bureau.

Since the educational requirements of staff members are varied and
changing, the NBS Educational Committee determines course offerings on
the basis of periodic need surveys. The program is flexible, including both
NBS in-hours courses and NBS-university-sponsored out-of-hours courses.
The Technician Career Program, established in 1960, offers a series of
in-hours courses on the fundamentals of science and mathematics. The
Program helps increase job efficiency and offers educational opportunities
to subprofessional laboratory personnel. A workshop in correspondence
management, one in filing, and a telephone training course was offered dur-
ing 1963. Since the establishment of the Washington educational program
in 1908, 42 universities have awarded 293 graduate degrees based partly
on credits obtained or thesis work carried on under the NBS Graduate
School Program.

The Bureau has expanded the Graduate Program at Boulder through the
establishment of a Joint-Course program and an Adjoint Professor plan with

210

the University of Colorado. Various graduate departments at both the NBS
Graduate School and the University offer courses simultaneously, with
benefits to both the Government and the University. Bureau staff members
who teach the courses have the title of Adjoint Professor at the University.

During the summer of 1963, an intensive three-week course in Electro-
magnetic Measurements and Standards was offered at Boulder in coopera-
tion with the University of Colorado. Participants in the course included
not only NBS staff members, but also employees from other government
agencies, industry, universities, and foreign research laboratories.

Nongovernment training, authorized by the Government Employees Train-
ing Act of 1958, falls into three major categories. These are:

1. Full-time (3 to 12 months) postdoctoral study and research assign-
ments at universities and research centers, both in this country and abroad.

2. Full-time (less than 3 months) attendance at institutes, seminars, short
concentrated courses, workshops, etc. Generally, these are offered through
the educational facilities of major universities and industrial laboratories
throughout the country.

3. Part-time, job-related academic courses at local educational institutions,
generally in early evening classes.

Approximately 425 staff members at Washington and Boulder were trained
through nongovernment facilities in 1963; fourteen career scientists were
selected for full-time research assignments at universities and research cen-
ters. Participants in approved full-time nongovernment training programs
receive full salary and expenses, including tuition, related fees, travel, and
per diem, as well as transportation of family and household effects.

Short concentrated courses and training programs at universities and in
industry were attended by forty-six Washington staff members. One hundred
thirty-nine Washington employees, mostly from technical divisions, attended
job-related courses at local educational facilities.

The Bureau sponsors a student trainee summer program for college stu-
dents majoring in the physical sciences, mathematics, and certain branches
of engineering. Each summer an integrated work-study program including
lectures, tours, demonstrations, supervised laboratory assignments, and pro-
fessional counseling, is conducted. The program acquaints young people
interested in career scientific research opportunities with the work being
done at NBS. One of the purposes of the program is to help in preparing
talented students for scientific careers. The enrollment in the 1963 student
program was two hundred thirty-nine students, which included eleven high
school students who were winners in the Westinghouse Science Talent Search
or other national science contests. The students participating in the program
came from schools throughout the country; many of the participants in the
program were graduate students.

In collaboration with the National Research Council, the Graduate School
offers postdoctoral resident research associateships to young scientific inves-
tigators of unusual ability and promise of becoming creative leaders in basic
research in the various branches of the physical and mathematical sciences.

211

While acquiring basic knowledge, they have opportunities to develop new
scientific approaches and laboratory skills, and thus advance scientific knowl-
edge. Twenty new Research Associateships (tenable at both the Wash-
ington and Boulder Laboratories) are open each year. During 1963, the
following young men were selected and served: Stanley Abramowitz, Robert
L. Brown, Halbert H. Carmichael, George E. Chamberlain, Richard F.
Demar, James E. Faller, Marcel L. Halberstadt, Eugene C. Johnsen, Robert
H. Kastl, David M. Larsen, Joseph A. Pirog, Duncan E. Poland, Albert
Romano, Joe D. Simmons, Robert E. Simpson, John W. Stewart, Tannie
Stovall, Joseph L. Thompson and George H. Thomson.

Scientific staff meetings, held weekly from September through May, are
also included in the Bureau's educational program. The staff meetings are
of a less specialized nature than colloquia and seminars offered in the Grad-
uate School program. They are open to all professional staff members of
the Bureau and to scientific personnel from neighboring laboratories.

3.7. PUBLICATIONS* AND PATENTS

Publications in the Bureau's Series

Journal of Research. Contains full research papers, including laboratory data, ex-
perimental procedures, and theoretical and mathematical analyses. Advances in meas-
urement standards and techniques . . . physical constants . . . properties of materials
. . . instrumentation . . . radio propagation.

The Journal is published in four separate sections . . .

A. Physics and Chemistry, issued six times a year. Annual subscription: Domestic,

$4; foreign, $4.75. Single copy, 70 cents.

B. Mathematics and Mathematical Physics, issued quarterly. Annual subscription:

Domestic, $2.25; foreign, $2.75. Single copy, 75 cents.

C. Engineering and Instrumentation, issued quarterly. Annual subscription: Do-

mestic, $2.25; foreign, $2.75. Single copy, 75 cents.
**D. Radio Propagation, issued six times a year. Single copy, 75 cents.
The papers listed below have appeared in the four-section Journal since June 1962.

Volume 66A (Phys. and Chem.), No. 4 (July-Aug. 1962)

Dielectric properties of semicrystalline polychlorotrifluoroethylene. A. H. Scott, D. J.

Scheiber, A. J. Curtis, J. I. Lauritzen, Jr., and J. D. Hoffman.
Thermal degradation of fractionated high and low molecular weight polystyrenes. S. L.

Madorsky, D. Mclntyre, J. H. O'Mara, and S. Straus.
Synthesis of 2-propoxy-5-methylbenzoic acid. G. M. Brauer and L. Simon.
The gamma-ray distribution from oriented cerium-141. J. F. Schooley, D. D. Hoppes,

and A. T. Hirshfeld.
Light source for producing self-reversed spectral lines. J. Sugar.
A diamond cell for X-ray diffraction studies at high pressures. G. J. Piermarini and

C. E. Weir.
Thermal conductivity of gases. I. The coaxial cylinder cell. L. A. Guildner.
Thermal conductivity of gases. II. Thermal conductivity of carbon dioxide near the

critical point. L. A. Guildner.
Derivation of the relaxation spectrum representation of the mechanical response function.

R. S. Marvin.
Intermediate phases in superconducting niobium-tin alloys. L. L. Wyman, J. R. Cuthill

G. A. Moore, J. J. Park, and H. Yakowitz.

*Publications for which a price is indicated are available by purchase from the Superintendent of
Documents, U.S. Government Printing Office, Washington, D.C., 20402 (foreign postage, one-fourth addi-
tional) . Reprints from outside journals and the NBS Journal of Research may often be obtained directly
from the authors.

** Changed to Radio Science in January 1961, issued monthly. Annual subscription: Domestic, $9;
foreign, $11.50. Single copy, $1.00.

212

Volume 66A (Phys. and Chem.), No. 5 (Sept.-Oct. 1962)

Calorimetric calibration of an ionization chamber for determination of X-ray total beam

energy. J. S. Pruitt and S. R. Domen.
Zinc oxide as a standard substance in the solution calorimetry of portland cement.

E. S. Newman.
Nuclear optical model analysis of neutron elastic scattering for calcium. R. S. Caswell.
Pyrolysis of some polyvinyl polymers at temperatures up to 1,200 °C. S. Straus and

S. L. Madorsky.
Lattice frequencies and rotational barriers for inorganic carbonates and nitrates from

low temperature infrared spectroscopy. R. A. Schroeder, C. E. Weir, and E. R.

Lippincott.
Foreign gas broadening of the lines of hydrogen chloride and carbon monoxide. E. K.

Plyler and R. J. Thibault.
Monolayers of adipate polyesters at air-liquid interfaces. W. M. Lee, R. S. Stromberg,

and J. L. Shereshefsky.

Volume 66A (Phys. and Chem.), No. 6 (Nov.-Dec. 1962)

Heat of formation of nitronium perchlorate. A. A. Gilliland.

Phase equilibrium relations in the binary system bismuth sesquioxide-niobium pentoxide

R. S. Roth and J. L. Waring.
Elastic constants of rutile (Ti02). J. B. Wachtman, Jr., W. E. Tefft, and D. G. Lam, Jr.
Reaction of hardened portland cement paste with carbon dioxide. C. M. Hunt and L. A.

Tomes.
Titanium standards for hydrogen content. J. T. Sterling, F. J. Palumbo, and L. L.

Wyman.
Ultraviolet stability of crosslinked polycaprolactam systems. S. D. Bruck.
Spectral-line intensities and ^/-values in the first spectrum of copper. C. H. Corliss.
Batch adsorption from solution. W. V. Loebenstein.
Separation of hafnium from zirconium and their determination: separation by anion-

exchange. L. A. Machlan and J. L. Hague.

Volume 67A (Phys. and Chem.), No. 1 (Jan.-Feb. 1963)

Heat of formation of calcium aluminate monosulfate at 25 °C. H. A. Berman and

E. S. Newman.
2,3-Dimethylpentane and 2-methylhexane as a test mixture for evaluating highly efficient

fractionating columns. E. C. Kuehner.
Phase equilibrium relations in the Sc203-Ga203 system. S. J. Schneider and J. L.

Waring.
Analysis of two infrared bands of CH2D2. W. B. Olson, H. C. Allen, Jr., and E. K. Plyler.
Precise coulometric titrations of halides. G. Marinenko and J. K. Taylor.
Radial distribution study of vitreous barium borosilicate. G. J. Piermarini and S. Block.
Dynamic compressibility of poly (vinyl acetate) and its relation to free volume. J. E.

McKinney and H. Vera Belcher.
An investigation of the constitution of the mercury-tin system. D. F. Taylor and C. L.

Burns.
Effect of methyl bromide additions on the flame speed of methane. C. Halpern.

Volume 67A (Phys. and Chem.), No. 2 (Mar.-Apr. 1963)

Third spectrum of palladium (Pd in) . A. G. Shenstone.

Broadening of the rotational lines of carbon monoxide by HC1 and by argon. R. J.
Thibault, J. H. Jaffe, and E. K. Plyler.

Theory of frustrated total reflection involving metallic surfaces. T. R. Young and B. D.
Rothrock.

Quantitative metallography with a digital computer: application to a Nb-Sn super-
conducting wire. G. A. Moore and L. L. Wyman.

Moire fringes produced by a point projection X-ray microscope. S. B. Newman.

Cyclic polyhydroxy ketones. I. Oxidation products of hexahydroxybenzene (benzene-
hexol) . A. J. Fatiadi, H. S. Isbell, and W. F. Sager.

Effect of pressure and temperature on the refractive indices of benzene, carbon tetra-
chloride, and water. R. M. Waxier and C. E. Weir.

Pressure-density-temperature relations of fluid para hydrogen from 15 to 100 °K at
pressures to 350 atmospheres. R. D. Goodwin, D. E. Diller, Hans M. Roder, and L. A.
Weber.

A method for determining the elastic constants of a cubic crystal from velocity meas-
urements in a single arbitrary direction; application to SrTi03. J. B. Wachtman, Jr.,
M. L. Wheat and S. Marzullo.

213

Volume 67 A (Phys. and Chem.), No. 3 (May-June 1963)

An absolute calibration of the National Bureau of Standards Thermal Neutron Flux.

E. J. Axton.

Absorption bands of carbon dioxide from 5.3 to 4.6 microns. Arthur G. Maki, Earle

K. Plyler, and Robert J. Thibault.
Infrared spectrum of the v2-Ve band of C^C^He. Walter J. Lafferty and Karl K. Plyler.
Self-broadening of carbon monoxide in the 2v and 3v bands. Earle K. Plyler and

Robert J. Thibault.
Thermodynamic properties of polyethylene predicted from paraffin data. Martin G.

Broadhurst.
Spectrophotometric determination of the thermodynamic pK value of picric acid in

water at 25 °C. Marion Maclean Davis and Maya Paabo.
Purity analysis of highly purified materials by time-temperature cryometry. Gaylon S.

Ross and Herbert D. Dixon.
Synthesis of isomers of eugenol. Gerhard M. Brauer, Richard Warren Morris, and

Williard B. Howe.
Analysis of families of curves. John Mandel and Frank L. McCrackin.
A controlled atmosphere chamber. Charles L. Gordon and Rolf B. Johannesen.

Volume 66B (Math, and Math. Phys.), No. 3 (July-Sept. 1962)

The first run preceded by a quota. A. J. Goldman and B. K. Bender.

Two theorems on matrices. M. Newman.

Mill's ratio for multivariate normal distributions. I. R. Savage.

Angle as a fourth fundamental quantity. J. E. Romain.

Invalidity of Meixner's theorem in irreversible thermodynamics. R. E. Nettleton.

Selected bibliography of statistical literature, 1930 to 1957: VI. Theory of estimation

and testing of hypotheses, sampling distributions, and theory of sample surveys. L. S.

Deming.

Volume 66B (Math, and Math. Phys.), No. 4 (Oct.-Dec. 1962)

Reliability of a system in which spare parts deteriorate in storage. G. H. Weiss.

Estimation of dispersion parameters. W. A. Thompson, Jr.

Laguerre expansions for successive generations of a renewal process. G. H. Weiss.

Bounds on ratios of means. G. T. Cargo and 0. Shisha.

A model for the viscoelastic behavior of rubberlike polymers including entanglement

effects. R. S. Marvin and H. Oser.
Black box maximization of circular coverage. C. T. Zahn, Jr.
An application of information theory to the analysis of contingency tables, with a table

of In In n, n= 1 ( 1 ) 10,000. S. Kullback, M. Kupperman, and H. H. Ku.

Volume 67B (Math, and Math. Phys.), No. 1 (Jan.-Mar. 1963)

Evaluation of a generalized elliptic-type integral. L. F. Epstein and J. H. Hubbell.
An algorithm for obtaining an orthogonal set of individual degrees of freedom for

error. J. M. Cameron.
Recognition of completely mixed games. A. J. Goldman.
A new type of computable inductor. C. H. Page.
Numerical computation of the temporal development of currents in a gas discharge

tube. W. Bbrsch-Supan and H. Oser.
Tables of genera of groups of linear fractional transformations. H. Fell, M. Newman,

and E. Ordman.

Volume 67B (Math, and Math. Phys.), No. 2 (Apr.-June 1963)

Maximum cellular Boolean functions and perfect Gray codes. A. J. Goldman and B. K.

Bender.
The meaning of Betti's reciprocal theorem. C. Truesdell.
Effect of molecular weight on viscoelastic properties of polymers as predicted by a

molecular theory. H. Oser and R. S. Marvin.
Selected bibliography of statistical literature: supplement, 1958-1960. L. S. Deming.

Volume 66C (Eng. and Instr.), No. 3 (July-Sept. 1962)

Measurement of longitudinal spherical aberration in the extra-axial region of lenses.

F. E. Washer and W. R. Darling.

Spark-gap flashover measurements for steeply rising voltage impulses. J. H. Park and

H. N. Cones.
Evaporated-film electric hygrometer elements. F. E. Jones.

214

Methods of measuring the resistivities of anisotropic conducting media in situ. S.
Rush.

Corrosion of steel pilings in soils. M. Romanoff.

Corrosion rates of ferrous alloys (Fe-Cr and Fe-Cr-Si) measured by polarization tech-
nique. W. J. Schwerdtfeger.

A furnace for thermocouple calibrations to 2,200 CC. D. B. Thomas.

Total hemispherical emittance of coated and uncoated Tnconel and types 321 and 430
stainless steel. J. C. Richmond and W. N. Harrison.

'Mail Separator" control computer preliminary logical design. S. Henig and E. C.
Palasky.

Method of measuring emissivities of metals in the infrared. A. G. Maki and E. K.
Plyler.

Volume 66C (Eng. and Instr.), No. 4 (Oct.-Dec. 1962)

An ultra-high speed image dissecting camera for photographing strong shock waves.

K. B. Earnshaw and C. M. Benedict.
Biprism method of determining the equivalent focal length of flat field lenses. W. R.

Darling.
Effect of air drag on the motion of a filament struck transversely by a high-speed

projectile. F. L. McCrackin.
A precision noise spectral density comparator. C. M. Allred.
Stresses in a plate uniformly compressed over portions of its two opposite edges. M. Chi

and W. D. Kroll.
Studies of the stress-corrosion cracking of low-carbon steels. H. L. Logan.
A dual centrifuge for generating low-frequency sinusoidal accelerations. R. 0. Smith,

E. A. Willis, and J. S. Hilten.
Rotational micromanometers. K. Lofquist.
Study of gypsum plasters exposed to fire. J. V. Ryan.

Volume 67C (Eng. and Instr.), No. 1 (Jan.-Mar. 1963)

Method for calibrating a standard volt box. B. L. Dunfee.

Stability of residual thiosulfate in processed microfilm. C. I. Pope.

Equipment for single crystal growth from aqueous solution. J. L. Torgesen, A. T.

Horton, and C. P. Saylor.
An automatic multichannel correlator. R. F. Brown, Jr.
Elastic constant — porosity relations for polycrystalline thoria. S. Spinner, F. P.

Knudsen, and L. Stone.
An oxygen partial pressure warning instrument. L. Greenspan.
New fast-opening, large-aperture shutter for high-speed photography. E. C. Cassidy

and D. H. Tsai.
Equations for the radiofrequency magnetic permeameter. C. A. Hoer and A. L.

Rasmussen.

Volume 67C (Eng. and Instr.), No. 2 (Apr.-June 1963)

Temperature dependence of the elastic constants of thoria specimens of varying porosity.
S. Spinner, L. Stone, and F. P. Knudsen.

Residual stresses and their relaxation on the surfaces of sections cut from plastically
deformed steel specimens. Clarence J. Newton.

Permeation rates of electrolytic hydrogen and deuterium through iron. Joseph W. Pitts.

Steady state heat conduction in cylinders with multiple continuous line heat sources.
B. A. Peavy.

A radial-flow apparatus for determining the thermal conductivity of loose-fill insula-
tions to high temperatures. D. R. Flynn.

Analysis of a microwave radiometer for precise standardization of noise sources. Gray
D. Ward and John M. Richardson.

Realistic evaluation of the precision and accuracy of instrument calibration systems.
Churchill Eisenhart.

Volume 66D (Radio Prop.), No. 4 (July-Aug. 1962)

Propagation problems with space radio communications. K. Rawer.

On the absolute intensity of incoherent scatter echoes from the ionosphere. K. L. Bowles,

G. R. Ochs, and J. L. Green.
On the forward scattering of radio waves in the lower ionosphere. T. Hagfors.
Representation of diurnal and geographic variations of ionospheric data by numerical

methods. W. B. Jones and R. M. Gallet.
Interaction between an obliquely incident plane electromagnetic wave and an electron

beam in the presence of a static magnetic field of arbitrary strength. K. H. B. Wil-

helmsson.

714-691 0—64 15

215

An analysis of VLF mode propagation for a variable ionospheric height. J. R. Wait.

A method for the determination of lower ionosphere properties by means of field meas-
urements on sferics. F. B. Harris, Jr., and R. L. Tanner.

Defocusing of radio rays by the troposphere. R. E. Wilkerson.

Magnetotelluric fields in the frequency range 0.03 to 7 cycles per kilosecond: Part I.
Power spectra. C. W. Horton and A. A. J. Hoffman.

Magnetotelluric fields in the frequency range 0.03 to 7 cycles per kilosecond: Part II.
Geophysical interpretation. C. W. Horton and A. A. J. Hoffman.

Impedance of a circular loop in an infinite conducting medium. M. B. Kraichman.

Volume 66D (Radio Prop.), No. 5 (Sept.-Oct. 1962)

Theory of magneto-telluric fields. J. R. Wait

Propagation characteristics of magneto-ionic plasma columns. D. Formato and A.
Gilardini.

Dielectric loading of electric dipole antennas. J. Galejs.

Possible influence of the ionosphere on the impedance of a ground-based antenna. J. R.
Wait.

Some statistical theory for the analysis of radio propagation data. M. M. Siddiqui.

Auroral sporadic-/? ionization. R. D. Hunsucker and L. Owren.

Comparative study of the correlation of seasonal and diurnal cycles of transhorizon radio
transmission loss and surface refractivity. B. R. Bean, L. Fehlhaber and J. Grosskopf.

Enhancement of the lunar tide in the noon critical frequency of the F2 layer over the
magnetic equator. R. G. Rastogi.

Scattering from a conducting sphere embedded in a semi-infinite dissipative medium.
J. Galejs.

High-frequency scattering from a coated sphere. V. H. Weston and R. Hemenger.

Propagation of spherical waves through an ionosphere containing anisotropic irregular-
ities. K. C. Yeh.

Volume 66D (Radio Prop.), No. 6, (Nov.-Dec. 1962)

RF impedence probe measurements of ionospheric electron densities. J. A. Kane, J. E.

Jackson, and H. A. Whale.
Methods for applying numerical maps of ionospheric characteristics. W. B. Jones and

R. M. Gallet.
Very-low-frequency radio propagation in the ionosphere. D. W. Swift.
Prolonged space-wave fadeouts in tropospheric propagation. A. P. Barsis and M. E.

Johnson.
Range-error compensation for a troposphere with exponentially varying refractivity.

J. J. Freeman.
On the geometrical optics of curved surfaces with periodic impedance properties. C. J.

Marcinkowski and L. B. Felsen.
On the limitations of geometrical optics solutions for curved surfaces with variable im-
pedance properties. C. J. Marcinkowski and L. B. Felsen.
Conversion of the amplitude-probability distribution function for atmospheric radio

noise from one bandwidth to another. A. D. Spaulding, C. J. Roubique, and W. Q.

Crichlow.
Some statistical properties of pulsed oblique HF ionospheric transmissions. M. Balser

and W. B. Smith.
Induction in a small loop moving with a magnetostatic dipole toward a conducting half

space. M. B. Kraichman.
Propagation of terrestrial radio waves of long wavelength — theory of zonal harmonics

with improved summation techniques. J. R. Johler and L. A. Berry.
Terminal-zone corrections for a dipole driven by a two-wire line. K. Iizuka and R.

W. P. King.
Pattern synthesis with a flush-mounted leaky-wave antenna on a conducting circular

cylinder. A. Ishimaru and F. R. Beich.

Volume 67D (Radio Prop.), No. 1 (Jan.-Feb. 1963)

"A lunar theory reasserted" — a rebuttal. J. V. Evans.

Point-to-point communication on the moon. L. E. Vogler.

HF communication during ionospheric storms. G. E. Hill.

Use of surface refractivity in the empirical prediction of total atmospheric refraction.

W. R. IlifT and J. M. Holt.
Effective sunspot numbers, January 1961 through July 1962. W. B. Chadwick.
On the theory of radio wave propagation over inhomogenous earth. K. Furutsu.

216

Correction to "Fields of electric dipoles in sea water, the earth-atomsphere-ionosphere

problem". W. L. Anderson.
Composition of reflection and transmission formulae. J. Heading.
Titheridge coefficients for the polynomial method of deducing electron density profiles

from ionograms. A. R. Long and J. O. Thomas.
Input admittance of linear antennas driven from a coaxial line. T. T. Wu.

Volume 67D (Radio Prop.), No. 2 (Mar.-Apr. 1963)

The protection of frequencies for radio astronomy. R. L. Smith-Rose.

Radar reflections from the moon at 425 Mc/s. G. H. Millman and F. L. Rose.

Sunset and sunrise in the ionosphere : effects on the propagation of longwaves. J. Rieker.

Correction of atmospheric refraction errors in radio height finding. W. B. Sweezey and

B. R. Bean.
Empirical determination of total atmospheric refraction at centimeter wavelengths by

radiometric means. A. C. Anway.
Propagation of radiofrequency electromagnetic fields in geological conductors. V. Fritsch.

Translated from German by A. P. Barsis.
WWV reception in the arctic during ionospheric disturbances. G. E. Hill and John R.

Herman.
Height-gain for VLF radio waves. J. R. Wait and K. P. Spies.

Perturbation method in a problem of waveguide theory. D. Fox and W. Magnus.
Some wave functions and potential functions pertaining to spherically stratified media.

C.T.Tai.
Radiation from a plasma-clad axially-slotted cylinder. W. V. T. Rusch.
Two- and three-loop superdirective receiving antennas. E. W. Seeley.
Hallen's method in the problem of a cavity-bark rectangular slot antenna. J. Galejs.
Relative convergence of the solution of a doubly infinite set of equations. R. Mittra.

Volume 67D (Radio Prop.), No. 3 (May-June 1963)

Effects of radio wave propagation through mid-latitude 6300 A auroral arcs. J. R. Roach.
Comparison of observed atmospheric radio refraction effects with values predicted

through the use of surface weather observations. B. R. Bean and G. D. Thayer.
Ionospheric scattering effects in long-distance propagation. H. A. Whale.
Concerning solutions of the VLF mode problem for an anisotropic curved ionosphere.

James R. Wait.
On the statistical theory of electromagnetic waves in a fluctuating medium (I).

K. Furutsu.
Reception of skywave signals near a coastline. J. Bach Andersen.
Analysis and synthesis of nonuniform transmission lines or stratified layers. G. Latmiral,

G. Franceschetti, and R. Vinciguerra.
Resonant characteristics of a corrugated sphere. James R. Wait and Carolen M.

Jackson.
Impedances of long antennas in air and in dissipative media. D. W. Gooch, C. W.

Harrison, Jr., R. W. P. King, and T. T. Wu.
Reflection of VLF radio waves from an inhomogenous ionosphere. Part I. Expo-
nentially varying isotropic model. James R. Wait and Lillie C. Walters.

Technical News Bulletin. This monthly publication summarizes the current research,
development, and test activities of the Bureau. The articles are brief, with emphasis
on the results of research and their significance, chosen for their importance to other
scientists, engineers, and to industry. Resumes of longer research reports, important
national and international conferences on fudamental science in which the Bureau has
represented the Nation, and bibliography of all publications by members of the staff
as published are included. The Bulletin is designed to give a succinct account of the
current work of the Bureau. (Annual subscription: domestic, $1.50; foreign, $2.25.)

Central Radio Propagation Laboratory Ionospheric Predictions: This is a monthly
publication for those concerned with radio communication in determining the best
skywave frequencies over any path at any time of day for average conditions for the
month of prediction, which are made 3 months in advance. Charts of extraordinary-wave
critical frequency for the F2 layer and of maximum usable frequency for a transmis-
sion distance of 4,000 km, of highest frequency of sporadic E in excess of 15 Mc/s are
included. In addition, there are various maps, charts, diagrams, and nomograms needed
to make practical application of the world-contour charts, together with examples of their
use. (Annual subscription: domestic, $1.50; foreign, $2.00.)

217

Monographs. These are usually contributions to the technical literature which are
too lengthy for publication in the Journal of Research. They often provide extensive
compilations of information on subjects related to the Bureau's technical program.
Until July 1959 most of this type of material was published in the Circular series.

25. Standard X-ray diffraction powder patterns. Section 2. Data for 37 substances,
H. E. Swanson, M. C. Morris, R. P. Stinchfield, and E. H. Evans. May 3, 1963. 35
cents.

43. Chemistry of cement, Proceedings of the Fourth International Symposium, Wash-
ington 1960, Volume I. August 31, 1962, $6.50; Volume II. September 27, 1962. $6.25.

49. Tables of Einstein functions, vibrational contributions to the thermodynamic func-
tions, J. Hilsenrath and G. G. Ziegler, July 12, 1962. $2.75.

50. Bibliography on atomic transition probabilities, B. M. Glennon and W. L. Wiese,
August 1, 1962. 35 cents.

51. Analysis of electric energy usage in Air Force houses equipped with air-to-air heat
pumps, P. R. Achenbach, J. C. Davis, and W. T. Smith. July 13, 1962. 30 cents.

52. Annotated bibliography on soft X-ray spectroscopy, H. Yakowitz and J. R. Cuthill.
June 29, 1962. $1.00.

53. Experimental transition probabilities for spectral lines of seventy elements, C. H.
Corliss and W. R. Bozman, July 20, 1962. $4.25.

54. Analytical standards for trace elements in petroleum products, H. S. Isbell, R. S.
Tipson, J. L. Hague, B. F. Scribner, W. H. Smith, C. W. R. Wade and A. Cohen,
October 1, 1962. 25 cents.

55. NBS viscometer calibrating liquids and capillary tube viscometers, R. C. Hardy.
December 26, 1962. 20 cents.

56. Systems of electrical units, F. B. Silsbee. September 20, 1962. 30 cents.

57. Periodicals received in the Library of the National Bureau of Standards, July 1962,
N. J. Hopper, November 23, 1962. Supersedes NBS Circular 563 and the 1st Supple-
ment to NBS Circular 563. 25 cents.

58. Corrosion of steel pilings in soils, M. Romanoff, October 24, 1962. 20 cents.

59. Mechanical behavior of crystalline solids, Proceedings of an American Ceramic
Society Symposium, New York City, April 1962. March 25, 1963. $1.75.

60. Influence of a sector ground screen on the field of a vertical antenna, J. R. Wait
and L. C. Walters. April 15, 1963. 25 cents.

62. Testing of metal volumetric standards, J. C. Hughes and B. C. Keysar. April 1,
1963. 15 cents.

63. Tensile and impact properties of selected materials from 20 to 300° K, K. A. Warren
and R. P. Reed. June 29, 1963. 35 cents.

64. Refractive indices and densities of aqueous solutions of invert sugar, C. F. Snyder
and A. T. Hattenburg. June 7, 1963. 15 cents.

65. Reduction of data for piston gage pressure measurements, J. L. Cross. June 17, 1963.
15 cents.

Miscellaneous Publications. As the name implies, this series includes material, which,
because of its character or because of its size, does not fit into any of the other regular
publication series. Some of these are charts, administrative pamphlets, Annual Reports,
Weights and Measures Conference Reports, and other subjects appropriate to the
Miscellaneous series.

244. Report of the 47th National Conference on Weights and Measures 1962. November
23, 1962. 75 cents.

245. Hydraulic research in the United States, 1962, H. K. Middleton. October 26, 1962.
$1.00.

246. Research highlights of the National Bureau of Standards, Annual Report 1961.
December 1962. 70 cents.

Handbooks. These are recommended codes of engineering and industrial practices,
including safety codes, developed in cooperation with the national organizations and
others concerned. In many cases the recommended requirements are given official status
through their incorporation in local ordinances by State and municipal regulatory bodies.

83. Tabulation of data on receiving tubes, C. P. Marsden and J. K. Moffitt. May 23.
1963 (supersedes Handbook 68). $1.25.

84. Radiation quantities and units. International Commission on Radiological Units
and Measurements (ICRU) Report 10a, 1962. November 14, 1962. 20 cents.

88. Radiobiology dosimetry. Recommendations of the International Commission on
Radiological Units and Measurements (ICRU) Report lOe, 1962. April 30. 1963.
25 cents.

90. Handbook for CRPL Ionospheric Prediction based on numerical methods of mapping.
S. M. Ostrow. December 21, 1962 (supersedes Circular 465). 40 cents.

218

Technical Note Series. This series was initiated in 1959 to supplement the Bureau's
regular publications program. Technical Notes provide a means for making available
scientific data that are of transient or limited interest.

18-14. Quarterly radio noise data — March, April, May 1962 and corrigendum for Tech-
nical Notes 18-1 through 18-11, W. Q. Crichlow, R. T. Disney, and M. A. Jenkins.
August 9, 1962. 50 cents.

18-15. Quarterly radio noise data — June, July, August 1962, W. Q. Crichlow, R. T. Dis-
ney, and M. A. Jenkins. March 1, 1963. 45 cents.

40-8. Mean electron density variations of the quiet ionosphere, No. 8 — October 1959,
J W. Wright, L. R. Wescott, and D. J. Brown. September 1962. 35 cents.

40-9. Mean electron density variations of the quiet ionosphere, No. 9 — November 1959,
J. W. Wright, L. R. Wescott, and D. J. Brown. April 22, 1963. 35 cents.

40-10. Mean electron density variations of the quiet ionosphere, No. 10 — December 1959,
J. W. Wright, L. R. Wescott, and D. J. Brown. March 24, 1963. 35 cents.

98. Synoptic radio meteorology, B. R. Bean, J. D. Horn and L. P. Riggs. October 1962.
50 cents.

99. A survey of the techniques for measuring the radio refractive index, R. E. McGavin.
May 1962. 30 cents.

100. Required signal-to-noise ratios, RF signal power, and bandwidth for multichannel
radio communications systems, E. F. Florman and J. J. Tary. January 1962. $1.00.

103. Equipment characteristics and their relation to system performance for tropospheric

communication circuits, A. F. Barghausen, F. O. Guiraud, R. E. McGavin, S. Mura-

hata, and R. W. Wilber. January 15, 1963. $1.00.
120A. A tabulation of the thermodynamic properties of normal hydrogen from low

temperatures to 540° R and from 10 to 1500 psia, Supplement A (British units), J.

W. Dean. June 1962. 45 cents.
127. Bibliography on direction finding and related ionospheric propagation topics, 1955-

1961, O. D. Remmler. October 1962. 60 cents.
129A. The thermodynamic properties of nitrogen from 114 to 540°R between 1.0 and

3000 psia — Supplement A (British units) T. R. Strobridge. February 1963. 50 cents.
141. Controlled temperature oil baths for saturated standard cells, P. H. Lowrie, Jr.

August 1962. 25 cents.
145. Equatorial spread F, W. Calvert. August 1, 1962. 60 cents.

150. General characteristics of linear strain gage accelerometers used in telemetry, P. S.
Lederer. June 1962. 40 cents.

151. Mode conversion in the earth-ionosphere waveguide, J. R. Wait. June 8, 1962. 20
cents.

152. Coordinated color identifications for industry, K. L. Kelly. November 1962. 15
cents.

153. A general survey of the semiconductor field, G. W. Reimherr. August 1962.
30 cents.

154. The thermodynamic properties of helium from 3 to 300° K between 0.5 and 100
atmospheres, D. B. Mann. January 1962. 50 cents.

154A. The thermodynamic properties of helium from 6 to 540° R between 10 and 1500
psia, D. B. Mann. January 1962. 50 cents.

155. The energy parameter B for strong blast waves, D. L. Jones. July 1962. 25 cents.

157. Information selection systems retrieving replica copies: A state-of-the-art report,
T. C. Bagg and M. E. Stevens. December 31, 1961. $1.25.

158. Efficient use of the radio spectrum, K. A. Norton. April 1962. 45 cents.

159. A Fortran code for calculation of eigenvalues and eigenfunctions in real potential
wells, R. S. Caswell. August 1962. 25 cents.

160. Emission stabilization of thermionic diode noise sources. M. W. Randall and
M. G. Arthur. September 1962. 15 cents.

161. Evaluation of unexpectedly large radiation exposures by means of photographic
film, W. L. McLaughlin. August 1962. 15 cents.

162. Thermal balance of the F region of the atmosphere, D. C. Hunt. September 1962.
50 cents.

163. The construction of calorimeters for the measurement of absorbed dose, B. Petree
and G. Ward. November 1962. 25 cents.

164. On plasma collision frequencies proportional to energy in the radio wave reflection
and transmission process, J. R. Johler and J. D. Harper, Jr. March 1, 1963. 40 cents.

165. Fading correlation bandwidth and short-term frequency stability measurements on a
high-frequency transauroral path, J. L. Auterman. October 1962. 40 cents.

166. (PB181454). An atlas of whistlers and VLF emissions, A survey of VLF spectra
from Boulder, Colorado, D. L. Jones, R. M. Gallet, J. M. Watts, and D. N. Frazer.
January 1963. $2.25.**

**This publication is available by purchase from the Office of Technical Services, Department of Com-
merce, Washington, D.C.; order by PB number.

219

167. The error rates in multiple FSK systems and the signal-to-noise characteristics of
FM and PCM-FS systems, H. Akima. March 25, 1963. 40 cents.

168. Transistorized building blocks for data instrumentation, Roger L. Hill. April 1,
1963. 55 cents.

169. Profiles of electron density over the magnetic equator obtained using the incoherent
scatter technique, K. L. Bowles, et al. March 16, 1963. 25 cents.

170. Phototypesetting of computer output, W. R. Bozman. June 25, 1963. 10 cents.

171. Bibliography on atmospheric aspects of radio astronomy. Including selected ref-
erences to related fields, W. Nupen. May 1, 1963. $2.00.

172. Practical methods for calibration of potentiometers, D. Ramaley. March 25, 1963.
30 cents.

173. Tables to facilitate the determination of the ferrimagnetic resonance linewidth of
non-metallic magnetic materials, C. C. Preston and W. E. Case. April 15, 1963.
25 cents.

174. Research on crystal growth and defect characterization at the National Bureau of
Standards during the period July to December 1962, ed. H. S. Peiser. March 15, 1963.
25 cents.

175. Curves of ground proximity loss for dipole antennas, L. E. Vogler and J. L. Noble.
May 20, 1963. 30 cents.

177. Table of attenuation error as a function of vane-angle error for rotary vane at-
tenuators, W. Larson. May 20, 1963. 75 cents.

178. An interpolation procedure for calculating atmospheric band absorptions from
laboratory data, L. Droppleman, L. R. Megill, and R. F. Calfee. June 3, 1963. 20
cents.

185. Lectures on ion-atom collisions, M. R. C. McDowell. March 15, 1963. 40 cents.

186. Tabulation of published data on Soviet electron devices, C. P. Marsden. June 3,
1963. 45 cents.

187. Transmission and reflection of electrons by aluminum foils, M. J. Berger. April 1,
1963. 15 cents.

188. Calibration of volt-ampere converters, E. S. Williams. April 25, 1963. 20 cents.

191. Tables describing small-sample properties of the mean, median, standard deviation,
and other statistics in sampling from various distributions, C. Eisenhart, L. S. Deming,
and C. S. Martin. June 14, 1963. 20 cents.

192. Calculations of the potential and effective diffusion constant in a polyelectrolyte
solution, S. R. Coriell and J. L. Jackson. June 28, 1963. 25 cents.

194. National standard reference data program. Background information. June 1963.
25 cents.

Publications in Outside Journals*

Achenbach, P. R., Mechanical design of protected areas, Proc. BRI Conf. Design for
Nuclear Age, 992, 21-49 (1962) .

Achenbach, P. R., Kusuda, T., Drapeau, F. J. J., Mathematical analysis of thermal en-
vironment in underground shelters, ASHRAE Symp. Survival Shelters, pp. 9-33
(June 1962).

Agy, V., Polar blackout during the International Geophysical Year, Intern. Conf. Cosmic
Rays and the Earth Storm, Proc. Tokyo Phys. Soc. Japan 1, 121 (1962) .

Ailor, W. H., Jr., Reinhart, F. M., Ten years weathering data on aluminum allovs, Ma
terials Protect. 2, No. 6, 30-36 (June 1963).

Akima, H., The error rate in a multiple frequency shift system and the output SNR in
an FM and a PCM-FS system, Conf. Digest of Intern. Conf. Satellite Communication.
London, England, pp. 305-310 (Dec. 1962) .

Allen, H. C, Jr., Cross, P. C, Molecular vib-rotors, John Wiley & Sons Inc., New York,
N.Y., (1963).

Allen, H. C, Jr., Olson, W. B., Sum rules for vibrational-rotational energy levels includ-
ing centrifugal distortion, J. Chem. Phys. 37, No. 2, 212-214 (July 1962).

Allen, H. C, Jr., Olson, W. B., Vibrational-rotational spectroscopy, Ann. Rev. Phys.
Chem. 13, 221-240 (1962).

Alt, F. L., Digital pattern recognition by moments, Book, Optical Character Recognition,
ed. G. L. Fischer, D. K. Pollack, B. Raddick, and M. E. Stevens, Pt. II, pp. 153-179
(Spartan Books, Washington, D.C., 1962) .

Alt, F. L., Safety levels in military inventory management, Operations Res. 10, No. 6.
786-794 (Dec. 1962).

Ambler, E., Nuclear orientation, Book, Methods of Experimental Physics 5, Sec. 2.4-2.3.
162-214 (Academic Press Inc., New York, N.Y., 1963) .

Ambler, E., Eisenstein, J., Schooley, J., Traces of products of angular momentum mat-
rices II. Spherical basis, J. Math. Phys. 3, No. 4, 760-771 (July-Aug. 1962) .

*For completeness, a few references to publications issued previous to July 1962 are included.

220

Ames, L. L., White, D., Mann, D. E., Infrared absorption spectra of carbon suboxide and

malononitrile in solid argon matrices, J. Chem. Phys. 38, No. 4, 910-917 (Feb. 1963).

Anderson, M. M., Transparent rigid mount for vacuum stopcocks, Rev. Sci. Instr. 34, No.

2, 187 (Feb. 1963).
Armstrong, G. T., Marantz, S., Heats of formation of two isomers of difluorodiazine, J.

Chem. Phys. 38, No. 1, 169-172 (Jan. 1963) .
Arnett, R. W., Millhiser, D. R., Probert, W. H., Experimental determination of the
bulk density of boiling liquid oxygen, Advan. Cryog. Eng. 8, Paper E-4, 256-262
(1963).
Arp, V. D., Kropschot, R. H., Helium, Book, Applied Cryogenic Engineering, Ed. R. W.

Vance, Ch. 12, 321-343 (John Wiley & Sons, Inc., New York, N.Y., 1962).
Arp, V. D., Kropschot, R. H., Craig, T. S., The intermediate state of some hard supercon-
ductors, Book, Superconductors, pp. 135-141 (Interscience Publ., New York, N.Y.,
1962).
Astin, A. V., Physical measurement: pilot of progress, Steel, p. 112 (July 23, 1962).
Astin, A. V., Some problems of improving accuracy of measurement, IRE Conv.. Record,

Pt. 9, pp. 9-17 (1962).
Astin, A. V., The basis of the measuring system, Proc. IRE 50, No. 5, 614-615 (May

1962).
Atkinson, W. R., Key, L., Newman, I., Spectrum analysis of extremely low frequency

variations of quartz oscillators, Proc. IEEE 51, No. 2, 379 (Feb. 1963).
Ausloos, P. J., Lias, S. G., Radiolysis of methane, J. Chem. Phys. 38, No. 9, 2207-2214

(May 1,1963).
Ausloos, P., Rebbert, R. E., Intramolecular rearrangements. V. Formation of ethylene in

the photolysis of ethyl acetate from 4 to 500 °K, J. Phys. Chem. 67, No. 1, 163-167
(Jan. 1963).
Axilrod, B. M., Comments on the Rosen interaction potential of two helium atoms, J.

Chem. Phys. 38, No. 1, 275-277 (Jan. 1963) .
Banerjee, M. K., Levinson, C. A., Meshkov, S., Calculations of energy spectra of nuclei

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Stair, R., The present status of radiometric calibrations in the ultraviolet spectrum, Report

No. Las-TR-199-37 (University of Chicago, Chicago, 111., Nov. 1962) .
Steiner, B., Seman, M., Branscomb, L. M., Electron affinity of iodine, J. Chem. Phys. 37,

No. 6, 1200-1202 (June 1962) .
Stern, J., An application of the peek-a-boo principle to information retrieval, Proc. Symp.

Materials Information Retrieval, pp. 93-115 (Nov. 28-29, 1962).
Stern, J., Communication in electronics, Signal 16, No. 10, 78-79 (June 1962) .
Stern, K. H., Electrode potentials in fused systems. VI. Membrane potentials. J. Phys.

Chem. 67, No. 4, 893-895 (Apr. 1963) .
Stern, K. H., Oxidation of metals in salts. Silver in sodium chloride, J. Phys. Chem. 66,
. No. 7, 1311-1317 (July 1962).

Stevens, M. E., Mechanical reading of characters and recognition (Proc. Intern. Patent
Office Workshop on Information Retrieval) , 125th Anniversary of the U.S. Patent
Act of 1836, Pt. II, p. 205 ( 1962) .
Stewart, R. B., Smith, R. V., Strobridge, T. R., Current trends and prospects in cryo-
genics, a review of the 1962 Cryogenic Engineering Conference, Cryogenics 2, No. 6,
321-324 (Dec. 1962).
Stimson, H. F., The text revision of the international temperature scale of 1948, Book,
Temperature, Its Measurement and Control in Science and Industry 3, Pt. I, 59-66
( Reinhold Publ. Corp., New York, N.Y., 1962) .
Stimson, H. F., Swindells, J. F., Wilson, R. E., Temperature scales, thermocouples, and
resistance thermometers, American Institute of Physics Handb. 2d edition, Sec. 4a,
pp. 4-2-4-21 (1963).
Streever, R. L., Nuclear moment of Ni61 from nuclear resonance studies in steady external

magnetic fields, Phys. Rev. Letters 10, No. 6, 232-234 (Mar. 1963) .
Streever, R. L., Bennett, L. H., LaForce, R. C, Day, G. F., Nuclear Magnetic resonance
of Ni61 in dilute alloys of nickel in cobalt, Phys. Rev. 128, No. 4, 1632-1633 (Nov. 15,
1962).
Streever, R. L., Bennett, L. H., LaForce, R. C, Day, G. F., Nuclear resonance and the
hyperfine field in dilute alloys of nickel in iron, J. Appl. Phys. Suppl. Magnetism 34,
^ No. 4, Pt. 2, 1050-1051 (Apr. 1963) .

Swartzendruber, L. J., Applications of a semiconductor surface-state charge-storage device,
Book, Solid State Electronics 6, 59-61 (Pergamon Press Inc., New York, N.Y., 1963).

241

Tao, K., A theoretical study of sporadic-^ structure in the light of radio measurements,

Book, Ionospheric Sporadic E, ed. E. K. Smith and S. Matsushita, pp. 235-257 (Perga-

mon Press Inc., New York, N.Y., 1962) .
Tao, K., On the theoretical study of F scatter. J. Geomagnetism and Geolectricity 14,

71-85 (1962) ; J. Rad. Res. Tales (Japan) 9, 407 (Sept. 1962).
Tao, K., Wait, J. R., Reflection mechanisms for sporadic E, Book, Ionospheric Sporadic

E, ed. E. K. Smith and S. Matsushita, pp. 13-27 (Pergamon Press Inc., New York

N.Y., 1962).
Taylor, J, K., Analytical chemistry — a challenging profession, J. Assoc. Offic. Agric.

Chem. 46, 63-67 (Feb. 1963) .
Taylor, L. S., Radiation, Americana Annual, pp. 620-622 (Americana Corp., Chicago,

111., 1961).
Taylor, L. S., Radiation and the world we live in, Radiology 80, No. 3, 358-368 (Mar.

1963).
Taylor, L. S., Radiation effects on man, Nucleonics 21, No. 3, 58-60 (Mar. 1963).
Tchen, C. M., Landau damping with collective correlation, Czechoslovak J. Phys. 12,

516 (1962).
Thomas, A. M., Johnson, D. P., Little, J. W., Design of an interferometric oil manometer

for vacuum measurements, 1962 Trans. Ninth Natl. Vacuum Symp., American Vacuum

Society, Pt. Ill, pp. 468-473 ( 1962 ) .
Thomas, R. N., A question regarding atmospheres with a temperature inversion, J. Quant.

Spectry. Radiative Transfer 3, 133-135 (Apr.-June 1963).
Thomas, R. N., Comment on empirical inference of Doppler widths, Astrophys. J. 137,

No. 1,38-40 (Jan. 1963).
Thomas, R. N., Comments on the use of net rate processes and the equivalent two level

atom in non-LTE computations, Ann. Astrophys. 23, No. 6, 871-878 (1961).
Thomas, R. N., On the extension of the low-chromosphere model to the region of origin

of the UV solar spectrum (Proc. 10th Astrophysical Symp., Liege, Belgium), Mem.

Roy. Soc. Belgium 20, 305 (1961) .
Thomas, R. N., Pecker, C, Some limits on the effect of coronal self-emission upon the

excitation state of coronal ions, Astrophys. J. 137, No. 3, 967-980 (Apr. 1, 1962) .
Thompson, W. A., Jr., Precision of simultaneous measurement procedures, J. Am. Stat.

Assoc. 58, No. 302, 474-479 (June 1963) .
Tilley, W. R., Scientific information activities at the National Bureau of Standards

(53d Special Libraries Assoc. Conv., Metals Division, May 29, 1962, Washington, D.C.) ,

Spec. Lib., pp. 29-34 (Jan. 1963) .
Timmerhaus, K. D., Low-temperature thermometry, Book, Applied Cryogenic Engineer-
ing, ed. R. W. Vance, Ch. 4, pp. 60-103 (John Wiley & Sons, Inc., New York, N.Y.,

1962).
Timmerhaus, K. D., Drayer, D. E., Dean, J. W., An experimental investigation of over-all

heat transfer coefficients for condensing and boiling hydrogen films, Intern. Develop.

Heat Transfer ( ASME ) 2, 270-278 ( 1961 ) .
Torgesen, J. L., Horton, A. T., Electrolytic conductance of ammonium dihydrogen

phosphate solutions in the saturation region, J. Phys. Chem. 67, 376-381 (Feb. 1963) .
Trees, R., Non-linear effects in spectra of the iron group, Phys. Rev. 129, No. 3, 1220-1224

(Feb. 1,1963).
Truesdell, C. A., Mechanical basis of diffusion, J. Chem. Phys. 37, No. 10, 2336-2344

(Nov. 15, 1962) ;
Truesdell, C. A., Second-order effects in the mechanics of materials, Proc. Intern. Union

Theoretical and Applied Mechanics Symp. (Haifa, Israel, 1962) .
Tryon, M., Horowitz, E., Methods for the analysis of rubber and related products, Analyti-
cal Chemistry Handb. Sec. 13, pp. 233-256 (McGraw-Hill Book Co., Inc., New York,

N.Y., 1963).
Tryon, M., Wall, L. A., Oxidation of high polymers, Book, Autoxidation and Antioxidents.

ed. W. O. Lundberg, II, Ch. 19, 919-984 (Interscience Publ. Inc., New York, N.Y.,

1962).
Tsai, D. H., Park, J. H., Calorimetric calibration of the electrical energy measurement in

an exploding wire experiment (Proc. 2d Conf. Exploding Wire Phenomenon, Boston.

Mass., Nov. 1961), Book, Exploding Wires, ed. W. G. Change and H. K. Moore 2.

97-107 (Plenum Press, Inc., New York, N.Y., July 1962) .
Tyler, W. P., Tryon, M., Analysis of rubber and rubber products. Book, Standard

Methods of Chemical Analysis, Vol. IIB, Industrial and Natural Products and Non-
instrumental Methods, 6th ed., F. J. Welcher, Ch. 43, pp. 2146-2226 (D. Van

Nostrand Co., New York, N.Y., 1963).
Van Valkenburg, A., Visual observations of high pressure transitions. Rev. Sci. Instr.

Letter 33, No. 12, 1462 (Dec. 1962).
Vogler, L. E., Lunar point-to-point communication. Book, Technology of Lunar Explora-
tion, Progress in Astronautics and Aeronautics 9, 533-559 (Academic Press Inc., New

York,N.Y., 1963).

242

Wachtman, J. B., Jr., Peiser, H. S., Symmetry conditions for internal friction caused by
jumping of point defects in crystals, J. Appl. Phys. Letters 1, No. 1, 20-22 (Sept. 1962) .

Wachtman, J. B., Jr., Scuderi, T. G., Cleek, G. W., Linear thermal expansion of aluminum
oxide and thorium oxide from 100° to 1100 °K, J. Am. Ceram. Soc. 45, No. 7, 310-323
(July 1962).

Wagman, D. D., Evans, W. H., Halow, I., Dudley, R. M., Temperature, pressure, heat, and
entropy change of transition, fusion, and vaporization, American Institute of Physics
Handb. 2d ed., Sec. 4j, pp. 4-170-4-216 (1963) .

Wait, J. R., A note on diurnal phase changes of very-low-frequency waves for long paths,
J. Geophys. Res. 68, No. 1, 338-340 (Jan. 1, 1963) .

Wait, J. R., A note on E-held and //-field losses for ground-based antennas, Proc. IEEE
51, No. 2, 366 (Feb. 1963).

Wait, J. R., A note on the propagation of electromagnetic pulses over the earth's surface,
Can. J. Phys. 40, 1264-1268 ( 1962) .

Wait, J. R., A phenomenological theory of overvoltage for metallic particles, Book, Over-
voltage Research and Geophysical Applications, ed. J. R. Wait, Ch. 3, p. 22 (Pergamon
Press Inc., New York, N.Y., 1959) .

Wait, J. R., Comment on "The mode theory of VLF radio propagation for a spherical
earth and a concentric anisotropic ionosphere, Cf?n. J. Phys. Note 41, 819 (May 1963).

Wait, J. R., Effective impedance of a wire grid parallel to the earth's surface, IRE Trans.
Ant. Prop. AP-10, No. 5, 538-542 (Sept. 1962).

Wait, J. R., Electromagnetic waves in stratified media, Pergamon Press Inc., New York,
N.Y., 1962.

Wait, J. R., Excitation of modes at very low frequency in the earth-ionosphere waveguide,
J. Geophys. Res. 67, No. 10, 3823-3828 (Sept. 1962) .

Wait, J. R., Introduction to the theory of VLF propagation, Proc. IRE 50, 1624-1647
(July 1962).

Wait, J .R., On the propagation of ELF pulses in the earth-ionosphere waveguide, Can. J.
Phys. 40, 1360-1369 ( Oct. 1962 ) .

Wait, J. R., Preface to special issue on Electromagnetic Waves in the Earth, IEEE Trans.
Ant. Prop. AP-11, 206 (May 1963) .

Wait, J. R., The possibility of guided electromagnetic waves in the earth's crust, IEEE
Trans. Ant. Prop. Spec. Issue on Electromagnetic Waves in the Earth AP— 11, No. 3,
330-335 (May 1963).

Wait, J. R., The variable-frequency method, Book, Overvoltage Research and Geophysical
Applications, ed. J. R. Wait, Ch. 4, p. 29 (Pergamon Press Inc., New York, N.Y., 1959) .

Wait, J. R., Very low frequency propagation in the earth-ionosphere waveguide of non-
uniform width, Proc. Intern. Conf. Ionosphere, July 1962, pp. 446-451 (Institute of
Physics and the Physical Society, London, England, 1963).

Wait, J. R., Very low frequency propagation — theory and experiment, Monograph, Elec-
tromagnetic Waves in Stratified Media, Ch. IX, 264-288 (Pergamon Press Inc., Oxford,
England, 1962).

Wait, J. R., Wave propagation around a curved boundary which contains an obstacle,
Can. J. Phys. 40, 1010-1016 (Aug. 1962) .

Wait, J. R., Collett, L. S., Criteria from the transient decay curves, Book, Overvoltage
Research and Geophysical Applications, ed. J. R. Wait, Ch. 6a, p. 71 (Pergamon
Press Inc., New York, N.Y., 1959 ) .

Wait, J. R., Walters, L. C, Curves for ground wave propagation over mixed land and
sea paths, IEEE Trans Ant. Prop. AP-11, No. 1, 38-45 (Jan. 1963) .

Wall, L. A., Flynn, J. H., Degradation of polymers, Rubber Chem. Tech. 35, No. 5, 1157-
1221 (Dec. 1962).

Wall, L. A., Ingalls, R. B., Crosslinking of polymers induced by excited species, J. Poly-
mer Sci. Letter 62, No. 173, S5-S6 (Nov. 1962) .

Warwick, C. S., Corrections to the National Bureau of Standards list of IGY flares, IGY
Solar Activity Rept. 17 (1963) .

Warwick, C. S., Delay time of polar-cap blackout and its relation to delay of geomagnetic
disturbance, J. Geophys. Res. 68, No. 5, 1561-1562 (Mar. 1963).

Warwick, C. S., Propagation of solar particles and the interplanetary magnetic field
(Proc. Intern. Conf. Cosmic Rays and the Earth Storm), J. Phys. Soc. Japan 17,
Suppl. A, Pt. I, 571-572 ( 1962) .

Warwick, C. S., Solar particles in interplanetary space, Sky and Telescope 27, No. 3,
133-136 (Sept. 1962).

Warwick, C. S., The effect of geomagnetic crochet on cosmic-ray intensity, J. Geophys.
Res. 68, No. 10, 3303-3304 (May 1963) .

Warwick, C. S., The sudden ionospheric disturbance (Proc. Corfu Summer School, June
1962), Book, Radio Astronomical Studies of the Atmosphere, pp. 457-475 (North-
Holland Publ. Co., Amsterdam, The Netherlands, 1963).

Washer, F. E., Calibration of photogrammetric lenses and cameras at the National Bu-
reau of Standards, Photogrammetric Eng. XXIX, No. 1, 113-119 (Jan. 1963).

243

Washer, F. E., The precise evaluation of lens distortion, Photogrammetric Eng. XXXI,

No. 3,327-332 (Mar. 1963).
Waters, D. M., Smith. D., Thompson, M. C, Jr., Precision phase meter, IRE Trans. Instr.

1-11, No. 2, 64-66 (Sept. 1962) .
Weaver, F. D., Achievement of measurement agreement among electrical standards lab-
oratories, Instr. Control System 36, 128-131 (July 1962).
Webster, D. 0., The Hall effect, Student Quart, and EE Digest 1, No. 1, 82-86 (Joint

Publ. Am. Inst. Elec. Engr. and IRE, Sept. 1962) .
Weinstock, J., On the three-particle scattering operator in classical gases, Physical Let-
ters 3, No. 6, 260-262 (Amsterdam, The Netherlands, Feb. 1963).
Weiss, G., A survey of some mathematical models in the theory of reliabilitv, Book,

Statistical Theory of Reliability, ed. M. Zelen, pp. 3-54 (University of Wisconsin Press,

Madison, Wise, 1963).
Weiss, G., On the pedestrian queueing problem, Bull. ISI XXXIX, Pt. 4, 16.3-168 (1962).
Wells, J. S., Daywitt, W. C., Miller, C. K. S., Measurement of effective temperatures of

microwave noise sources, IRE Intern. Conv. Record Pt. Ill, pp. 220-238 (1962).
Weygand, F., Simon, H., Kell, K. D., Isbell, H. S., Sniegoski, L. T.. Isotope effect in the

recrystallization of D-mannose-1-f phenylhydrazone, Anal. Chem. 34, 1753-1755 (Dec.

1962).
Wichers, E., New scale of nuclidic masses and atomic weights, Nature 194, No. 4829,

621-624 (May 19, 1962).
Wichers, E„ Pure substance and measurement, Mater. Res. Std. 1, No. 4, 314-315 (Apr.

1961).
Wichers, E., The history of Pt. 27, Book, Temperature, Its Measurement and Control

in Science and Industry 3, Pt. 1, 259-262 (Reinhold Publ. Corp., New York, N.Y.,

1962).
Wichers, E., The role of the International Union of Pure and Applied Chemistry, J. Chem.

Doc. 3, No. 7, 7-11 (1963).
Wiese, W. L., Present status of our knowledge of atomic transition probabilities, Book,

Proc. Xth Colloquium Spectroscopicum Internationale, ed. E. R. Lippincott and M.

Margoshes, pp. 37-56 (Spartan Books, Washington, D.C., 1963).
Wiese, W. L., Paquette, D., Solarski, J., Profiles of Stark broadened Balmer lines in a

hydrogen, Phys. Rev. 129, No. 3, 1225-1232 (Feb. 1963).
Wildhack, W. A., Standards for the 70s, Ind. Res. 5, No. 3, 15-20 (Mar. 1963) .
Wilson, B. L., Research in ASTM, Mater. Res. Std. 2, No. 8, 694-695 (Aug. 1962).
Woelfel, J. B., Paffenbarger, G. C, Changes in occlusion of complete dentures caused

by a pipe habit: a case report, J. Am. Dental Assoc. 66, No. 4, 478-485 (Apr. 1963).
Woelfel, J. B., Paffenbarger, G. C, Sweeney, W. T., Dimensional changes in complete

dentures on drying, wetting, and heating in water, J. Am. Dental Assoc. 65, No. 4,

495-505 (Oct. 1962).
Wolfe, W. C, Spectrophotometry determination of hydroperoxide in diethyl ether, Anal.

Chem. 34, No. 10, 1328-1330 (Sept. 1962).
Wolford, R. K., Kinetics of the acid-catalyzed reaction of acetal in water-acetone solvents

at 15, 25, and 35°, J. Phys. Chem. 67, No. 3, 632-636 (Mar. 1963).
Wolford, R. K., Bates, R. G., Kinetics of the hydrolysis of acetal in iV-methylpropionamide-

water and 7V-/V-dimethylformamide-water solvents at 20, 25, 30, and 40°, J. Phvs.

Chem. 66, No. 8, 1496-1500 (Aug. 1962).
Woolley, H. W., A realistic diatomic potential function, J. Chem. Phys. 37, No. 6, 1307-

1316 (Sept. 1962).
Wright, J. R., Minesineer, R. R., The electrophoretic mobilitv of asphaltenes in nitro-

methane, J. Colloid Sci. 18, 223-236 (Mar. 1963).
Wright, J. W., Temperature control of the structure and variations of the quiet ionosphere,

Proc. Intern. Conf. Ionosphere, July 1962, pp. 19-25 (Institute of Physics and the

Physical Society, London, England, 1963) .
Wrieht, J. W., The lifetime movement of artificially produced electron clouds observed

with spaced ionosondes, J. Geophys. Res. 68, No. 10, 3011-3020 (May 15, 1963).
Wyckoff, H. O., Quantities and units for dosimetry in diagnostic radiology. Symp. under

the auspices of the Division of Radiological Health, U.S. Public Health Service. Wash-
ington, D.C., Reduction of Patient Dosage from Diagnostic Radioliogy, ed. M. L. Jan-

ower, pp. 5-9 (Charles C. Thomas Publ., Springfield, 111., 1963).
Wyckoff, H. O., Allisy, A., Aston, G. H., Barnerd, G. P., Hubner. W.. Loftus. T. and

Taupin, G., Intercomparison of national roentgen and gamma-ray exposure-dose stand-
ards, Acta Radiol. 1, No. 1, 57-78 (Feb. 1963 f.
Wyman, L. L., Moore, G. A., Quantitative metallographic evaluations of graphitic micro-
structures, Modern Castings AFS 43, No. 1, 7-16 (Jan. 1963) .
Yahia, J., Dependence of the electrical conductivity and thermoelectric power of pure

and aluminum-doped rutile on equilibrium oxysen pressure and temperature. Phvs.

Rev. 130, No. 5, 1711-1719 (June 1, 1963).

244

Yokley, C. R., Shumaker, J. B., A computer for the Abel inversion, Rev. Sci. Instr. 34,

No. 5, 551-557 (May 1963).
Youden, W. J., Experimentation and Measurement, Book, published by the National

Science Teachers Association, Washington, D.C. (1962).
Youden, W. J., Graphical evaluation of analytical results, Proc. Conf. Chemical Control

Problems, pp. 1-15 (Sponsored by Natl. Plant Food Inst., Washington, D.C, 1959).
Youden, W. J., Memorial to Sir Ronald Aylmer Fisher: 1890-1962, J. Am. Stat. Assoc.

57, No. 300, 727-728 (Dec. 1962) .
Youden, W. J., Physical measurements and experiment design, Scuola Azione No. 10,

pp. 181-200 (Scuola de Studi Superiori Sugli Idrocarburi, San Donato Milanese, Italy,

1961-1962).
Youden, W. J., Ranking laboratories by round-robin tests, Mater. Res. Std. 3, No. 1,

9-13 (Jan. 1963).
Youden, W. J., Realistic estimates of error, J. ISA 8, No. 10, 57-58 (Oct. 1962).
Youden, W. J., Statistical interpretations, Book, Standard Methods for Chemical Analysis,

6th ed. IIA, Ch. 16, pp. 318-325 (D. Van Nostrand Co., Princeton, N.J., 1963).
Youden, W. J., Statistics in chemical analysis, Analytical Chemistry Handb. Sec. 14, pp.

14-1-14-9 (McGraw-Hill Book Co., Inc., New York, N.Y., 1963).
Youden, W. J., Uncertainties in calibration, IRE Trans. Instr. I— 11, Nos. 3 and 4, 133-138

(Dec. 1962).
Youden, W. W., Index to the communications of the ACM, 1958-1962, Commun. ACM 6,

No. 3, 1-32 (Mar. 1963).
Young, J. P., Discussion of electroforming solutions, ASTM Spec. Tech. Publ. 318, 26

(1962).
Younglove, B. A., Diller, D. E., The specific heat at constant volume of para-hydrogen

at temperatures from 15 to 90° K and pressures to 340 atm, Cryogenics 2, No. 6, 1-5

(Dec. 1962).
Younglove, B. A., Diller, D. E., The specific heat of saturated liquid para-hydrogen from

15 to 32° K, Cryogenics 2, No. 5, 283-287 (Sept. 1962).
Zahn, C. T., A new absolute null method for the measurement of magnetic susceptibili-
ties in weak low- frequency fields, Rev. Sci. Instr. 34, No. 3, 285-291 (Mar. 1963).
Zapf, T. L., The calibration of inductive voltage dividers, ISA 1962 Proc. 17, Pt. I,

10.2.62-1 to 10.2.62-8 (1962).
Zimmerer, R. W., Experimental investigation of Fabry-Perot interferometers, Proc. IEEE

51, No. 3, 475-476 (Mar. 1963) .
Zimmerer, R. W., New wavemeter for millimeter wavelengths, Rev. Sci. Inst. 33, No. 8,

858-859 (Aug. 1962).
Zimmerer, R. W., Anderson, M. V., Beers, Y., Strine, G. L., Millimeter wavelength res-
onant structures, IEEE Trans. Microwave Theory and Tech. MTT— 11, No. 2, 142-149

(Mar. 1963).
Zwanzig, R., Dielectric friction on a moving ion, J. Chem. Phys. 38, No. 7, 1603-1605

(Apr. 1963).
Zwanzig, R., Dielectric friction on a rotating dipole, J. Chem. Phys. 38, No. 7, 1605-1606

(Apr. 1963).
Zwanzig, R., Method for finding the density expansion of transport coefficients of gases,

Phys. Rev. 129, No. 1, 486-494 (Jan. 1963).

PATENTS

The following U.S. patents have been granted to NBS inventors; assigned (or
licensed as indicated) to the United States of America, as represented by the Secretary
of the department noted in parentheses:

Ayre, Vivian E., No. 3,041,465, June 26, 1962. Auxiliary power supply. (Navy.)
Bowen, Rafael L., No. 3,066,112, November 27, 1962. Dental filling material comprising

vinyl silane treated fused silica and a binder consisting of the reaction product of bis

phenol and glycidyl acrylate.
Bowman, Horace A., and Macurdy, Lloyd B., No. 3,074,498, Jan. 22, 1963. Device for

minimizing the effects of mal-centered balance pan loading.
Bowman, Horace A., No. 3,092,193, June 4, 1963. Substitution balance.
Brenner, Abner, and Reid, Walter E., No. 3,072,983, Jan. 15, 1963. Vapor deposition of

tungsten. (Navy)
Cordero, Fidel, and Armstrong, Richard W., No. 3, 078,719, Feb. 26, 1963. Airplane

cabin pressure error or deviation indicator. (Navy.)
Cordero, Fidel, and Armstrong, Richard W., No. 3,084,549, April 9, 1963. Aircraft cabin

pressure error indicator. ( Navy. )
Couch, Dwight E., Shapiro, Harold, Brenner, Abner, and Connor, Jean H., No. 3,046,205,

July 24, 1962. Nickel-aluminum alloy coatings. (Navy.)

245

Hardy, Richard J., Martin, Kenneth B., and Jacobs, Robert B., No. 3,054,289, Sept. 18,

1962. System for measuring net positive suction head of pumps.

Huntoon, Robert D., No. 3,069,113, Dec. 18, 1962. Antenna system for an ordnance

missile. (Navy.)
Jones, Frank E., No. 3,058,079, Oct. 9, 1962. Hygrometer elements. (Navy.)
Kaeser, Robert S., No. 3,052,064, Sept. 4, 1962. Glassblower's safety manostat and

system.
Kessler, Karl G., and Schweitzer, Walter G., Jr., No. 3,046,473, July 24, 1962. Very

narrow-pass filter using Zeeman-split absorption lines.
Koidan, Walter, No. 3,054,864, Sept. 18, 1962. Instrument for reciprocity calibration

of electroacoustic transducers. (Commerce.)
Lloyd, Edward C., Hutton, Ulric O., Johnson, Daniel P., and Zoranski, Henry J., No.

3,088,168, May 7, 1963. Multiple-anvil high pressure apparatus.
Mandelkern, Leo, and Roberts, Donald E., No. 3,090,735, May 21, 1963. Method for

making a fiber with reversible dimensional changes.
Marton, Ladislaus L., and Simpson, John A., No. 3,069,592, Dec. 18, 1962. Electro-
static filter lens or mirror.
Mason, Henry L., No. 3,079,080, Feb. 26, 1963. Crane warning system. (Navy.)
McClintock, Ralph M., No. 3,078,708, Feb. 26, 1963. Tensile cryostat. (Air Force.)
Nelson, Robert C., No. 3,093,820, June 11, 1963. Automatic radar monitor and alarm

device. (Licensed to the United States of America as represented by the Secretary

of Commerce.)
Orem, Theodore H., No. 3,060,065, Oct. 23, 1962. Method for the growth of preferentially

oriented single crystals of metals.
Pitts, Joseph W., No. 3,057,381, Oct. 9, 1962. Method and apparatus for stretch-forming

wire-grid strain gages. (Navy.)
Pummer, Walter J., and Wall, Leo A., No. 3,046,313, July 24, 1962. Preparation of penta-

fluoroiodobenzene (Navy.)
Pummer, Walter J., and Wall, Leo A., No. 3,075,018, Jan. 22, 1963. Tris-(pentafluoro-

phenyD-phosphine and method of making the same. (Navy.)
Ruehrwein, Robert A., No. 3,062,730, Nov. 6, 1962. Method of making ozone. (Army.)
Saunders, James B., No. 3,043,182, July 10, 1962. Interferometer for testing large

surfaces.
Shapiro, Gustave, No. 3,045,202, July 17, 1962. High frequency coaxial coupling.

(Navy.)
Silberstein, Richard, No. 3,095,538, June 25, 1963. Satellite relay station using an-
tenna diversity selection.
Weir, Charles E., Van Valkenburg, Alvin, and Lippincott, Ellis R., No. 3,079,505, Feb. 26,

1963. High-pressure optical cell.

Wexler, Arnold, Krinsky, Albert, and Garfinkel, Samuel B., No. 3,022,667, Feb. 27, 1963.
Adsorption electric hygrometer. (Navy.)

246

U.S. GOVERNMENT PRINTING OFFICE : 1964 O — 714-691

PENN STATE UNIVERSITY LIBRARIES

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AD00D7M11137

U. S. DEPARTMENT OF COMMERCE

;C^^- '"■'"'■■■' :— fS9$£. ■"■•■■ ■■'■:-: ■•■

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